'Coronation Street' star Simon Gregson has pulled out of filming.
The 40-year-old actor - who stars as Rovers Return landlord Steve McDonald in the ITV soap - has reportedly been hit by a mystery illness and will have to be temporarily written out of storylines while he waits for hospital test results.
Explaining that Corrie bosses aren't expecting him back on set "any time soon", a source said: "It's a frightening time for him. He's felt under the weather for a while, but it's recently got worse."
Simon - who has sons Alfie, seven, and five-year-old Harry with wife Emma Gleave - is said to have felt unwell while travelling home from a family day out last month and while he later went to the studios to film, he reportedly became too ill and had to go home.
Simon's character Steve has been seen sinking into depression following the murder of Tina McIntyre (Michelle Keegan) and while bosses were planning to develop the story into the New Year in order to raise awareness about mental health, it now seems they will have to have a rethink.
The source told The Sun newspaper: "The most important thing is Steve's health. He's a great guy and gives everyone a lift on set.
"It's a shock that he has had to pull out, especially when his character is so heavily involved in the storyline."
Meanwhile, Anne Kirkbride - who plays Deirdre Barlow - is currently taking an eight week break from the drama in order to "rest her bones", according to co-star Marc Baylis (Rob Donovan).

Jennifer Lopez is a "work in progress".
The 'On The Floor' hitmaker - who has six-year-old twins Max and Emme with ex-husband Marc Anthony - is learning to appreciate how "great" she is and thinks it is important to love herself before embarking on another relationship.
She said: "I would describe the woman I am today as a work in progress, a 'WIP'!
"And this was the beginning of what I think is going to be a life-long journey of being content and happy with myself.
"I have to know how great I am, you know--all of us need to know how great we are. That we're worth it...All of the things I'm involved with have the same message and it's that you must love yourself first, that the love that you're looking for is inside you."
The 45-year-old beauty believes everyone should put themselves first and be the "most important" person in their own lives.
She continued to E! News: "That sounds like a weird thing sometimes but it's so real, and when you can really appreciate the person you are--not what you've accomplished, not the money that you have...none of that, just the girl you are--that person is just a good, funny, generous loving person.
"You always have to be the most important [person in your life]. That's what love is."
While she has millions of fans around the world, the 'American Idol' judge used to take her critics to heart and was convinced everyone "hated" her.
She added: "We have a tendency to focus on the negative and I let that work on my self-esteem.
"I was always thinking that people didn't like me, they just hated me...It's such a ridiculous notion, we tend to do this to ourselves."

Kylie Jenner is being sued over a car accident last summer.
The 17-year-old reality star was involved in a three-car pile-up in August 2013 - just 18 days after her 16th birthday - when the Mercedes G-Wagon she was driving allegedly slammed into the back of a Toyota which was stopped in traffic.
The second vehicle then rear-ended a Subaru and the woman in that third vehicle is now taking legal action, accusing the 'Keeping Up with the Kardashians' star of being a negligent driver.
Additionally, Kylie's mother Kris Jenner is also being sued over the crash because the driver believes the showbiz matriarch to be the owner of the Mercedes, TMZ reports.
The woman's attorney claims she suffered injuries to her back and neck in the accident.
In August this year, Kylie was involved in another road accident when she reportedly made an illegal U-turn and smashed her $90,000 black Range Rover into an oncoming vehicle whilst driving through Katsuya in Glendale.
The other driver's lawyer also claimed the 17-year-old beauty was "aggressive" towards his client after the smash and even tried to persuade the alleged victim to not call the police in exchange for money.
However, Kylie reportedly told her parents immediately after the crash that a woman swerved into her lane and rear ended her.
The teenage star is also believed to have received multiple traffic tickets since getting her licence just over a year ago.

Daisy Lowe cried herself to sleep when she discovered Gavin Rossdale was her father.
The 25-year-old model found out at the age of 14 that the Bush frontman - who is now married to singer Gwen Stefani - was her biological father, and not a fertility specialist named Bronner Handwerger who she had been told was her dad.
She said: "That age is when you're at your most malleable; you're developing frontal lobes.
"But I'm very proud of those times 'cos at those moments when the s**t hits the fan I could either go out and get really f***ed up or I could go home, cry myself to sleep and wake up in the morning and give my mum a big cuddle, and feel better. And face it head-on."
The star - who has previously dated 'Doctor Who' actor Matt Smith and music producer Mark Ronson - made the discovery that Bronner was not her real father when she found out neither he nor her mother, singer-songwriter Pearl Lowe, shared her blood type. Pearl then admitted she had slept with the musician.
Recalling the period when the revelation emerged, she said: "[It was] a very interesting time."
Daisy - who has modelled for Burberry and Chanel - now likes to meditate and spend time with her friends to keep her grounded.
She told the London Evening Standard newspaper: "We all love to go out, have a good dance and play. But none of them is destructive.
"Some have been or could've been but not now. It seems like there's been a generational shift; that people are learning to look after their bodies earlier, (sic)"

Benedict Cumberbatch's future in-laws are "very happy" about his engagement to Sophie Hunter.
The 'Imitation Game' star announced his plans to marry his actress girlfriend yesterday (05.11.14) by posting a £270, plus VAT, notice in The Times newspaper, and the 36-year-old beauty's mother Katharine is overjoyed at the news.
She said: "We are very happy for them. It's a really fabulous day.
"It's only just been announced so we don't know any more but it's lovely news."
The 38-year-old actor looks to be a sure-fire hit with Sophie's family as her younger brother Patrick, 30, also admitted he approves of the pair's marriage plans.
He told the Daily Mirror newspaper: "We're all very happy for Soph - it's really exciting."
Benedict and Sophie's engagement, which appeared in the Births, Marriages and Deaths section of the broadsheet, read: "The engagement is announced between Benedict, son of Wanda and Timothy Cumberbatch of London, and Sophie, daughter of Katharine Hunter of Edinburgh and Charles Hunter of London."
It is not yet known when the couple - who first met when starring opposite one another in 2009's 'Burlesque Fairytales' - will walk down the aisle, but just last year the 'Sherlock' star insisted he was in no rush to tie the knot.
He said: "It's a wonderful thing to get married young and become a father.
"I used to think that I'd get married by my mid-thirties and have children.
"But now I think I can wait. I'm no longer in a hurry to get married."
The couple were first romantically linked in June when they were seen watching tennis together, and they were last spotted out and about at London restaurant Quaglino's but arrived separately and were keen not to be pictured together.

Channing Tatum is eyeing a role in 'The Hateful Eight'. The 34-year-old actor is circling a major role in the upcoming Western epic to be directed by 'Django Unchained' filmmaker Quentin Tarantino, Deadline reports. The 'Foxcatcher' star - who impres...

Jemma Bird thinks James Hill or Sanjay Sood-Smith should've been fired on 'The Apprentice' instead of her.
The 26-year-old star was booted off the BBC show last night (04.11.14) but she insists the pair were much more to blame for the failure of Team Summit's coach trip task - which Karren Brady described as the "trip from hell" - and thinks project manager Sanjay chose the easy way out by not selecting James to go into the boardroom.
She exclusively told BANG Showbiz: "I think James should have got fired. That was the kind of general standpoint, really. It seemed like that at the time but Sanjay made his decision and it ended up being me.
"James was psyching himself up to go in that boardroom as if he was about to go into a boxing match so I think Sanjay looked at the two of us and thought he'd rather take me on.
"I thought I'd be against Sanjay and James. They are very strong candidates and my card was marked to be honest.
"But Sanjay was owning up to a lot of things so I thought maybe I still had a chance because he made quite a few mistakes.
"I do think Sanjay made a lot of mistakes on that task, he did admit loads. You have to give him credit for holding his hands up and saying that he'd made mistakes."
While Jemma has admitted she doesn't have any regrets about her time on the show, she thinks she ultimately got fired by Lord Alan Sugar because she was "too well behaved" during the task.
She added: "My main downfall was probably not being much of an entertainer and being a bit too well behaved.
"I did things in the background which people obviously don't think are entertaining. So I got marked with the non-contribution card which was very frustrating."

Tina O'Brien had "11 days of hell" before giving birth.
The 'Coronation Street' actress and partner Adam Crofts welcomed their son Beau into the world last month and the 31-year-old beauty - who also has six-year-old daughter Scarlett with ex-boyfriend Ryan Thomas - admits she was struggling beforehand because she had gone so far past her due date.
She told OK! magazine: "I was 11 days overdue, which were 11 days of hell because I was still doing the school run with Scarlett and I was so heavy.
"The other mums would be like, 'Are you still pregnant?' "
While Tina remained calm during her two-hour labour, Adam was so stressed and nervous, he almost forgot to wait for his girlfriend before driving to hospital.
Tina revealed: "He was calm and loading up the car but when I had a contraction while I stood in the driveway, he suddenly became stressed and nearly drove off without me. Then he missed the junction so we ended up going the wrong way to the hospital.
"I didn't say much because I could tell he was pretty stressed. When we eventually got to the hospital, Adam marched through to the maternity unit and left me in the corridor having a contraction. I was like, 'Is he having the baby without me?' "
While little Scarlett is happy to have a baby brother, she has been a little confused about his name.
Tina said: "One of the mums in Scarlett's class said, 'Oh we've heard you called your son Ribbon' - Scarlett got confused between bow and ribbon!"

James Jordan wants to star in a reality TV show with Ola Jordan.
The 'Celebrity Big Brother' star says he and his wife, who have been married for 11 years, have "got nothing to hide" and would love to share their private lives via their own series.
Asked if he would let a camera crew into their house, the 36-year-old star told BANG Showbiz at the SeriousFun Children's Network Gala at London's Roundhouse: "It doesn't bother me, yeah. I mean Jesus Christ I did 'Big Brother' so yeah things like that don't bother me, I've got nothing to hide."
But James wouldn't allow filming to take place in their bedroom.
Discussing where they would draw the line, he said: "Probably when we're in the bedroom doing naughty things to each other ... I'm not really into porn. Not my bag really."
Fans of the couple could see their lives completely change if they do sign a deal to star in a reality TV series, as earlier this year, Ola, 32, admitted they eager to start a family.
The 'Strictly Come Dancing' star said: "I definitely don't want to sacrifice children for a career. I can't imagine life without kids and I think James will be a great dad."

Jake Bugg takes a ping pong table on tour with him.
The 'Lighting Bolt' singer recently completed a tour of the UK supported by up-and-coming duo Hudson Taylor, who revealed that the star is a dab hand at the table-top sport.
Alfie from the band exclusively told BANG Showbiz: "The interesting thing about the Jake Bugg tour was that there was a table tennis table, and that's where a lot of time was spent.
"Jake Bugg is very good at ping pong!"
The folk pop brothers - who will release their debut album 'Singing for Strangers' in February 2015, which will include their hits 'Chasing Rubies' and 'Battles' - confessed that they were no match for the 20-year-old musician's sports prowess, explaining that they only ever saw him get beaten once during the string of concerts.
Alfie added: "He's a very shy guy so we only really saw him when we were playing against him in table tennis.
"The only person to beat him that we experienced is a guy who plays with us, our violin player. He beat him and he was pretty chuffed with that."
Hudson Taylor performed at the Aloft London Excel to kick off the Live at Aloft Hotels - Spotlight Series. For more information, visit www.liveataloftlondonexcel.com

Miranda Lambert was the big winner at last night's (05.11.14) 48th annual Country Music Awards.
The 30-year-old star fought off stiff competition to win four different categories at the annual awards ceremony held at Nashville's Bridgestone Arena in Tennessee, which was hosted for the seventh time by singer Carrie Underwood and Brad Paisley.
The blonde beauty took home the Female Vocalist of the Year award for the fifth time, Album of the Year for 'Platinum', Single of the Year for her single 'Automatic' and she also shared the Musical Event of the Year gong with Australian singer Keith Urban for their collaboration 'We Were Us'.
Speaking as she collected her Female Vocalist prize, she said: "I don't know what to say. I can't believe I'm standing here. I can't believe this is my life ... Damn it! I cry every time."
Meanwhile, Miranda's husband Blake Shelton, 38 - whom she went up against in the Entertainer of the Year and Single of the Year categories - took home his fifth consecutive Male Vocalist of the Year award.
Other winners included 38-year-old Luke Bryan who took home his first ever CMA on the back of five hits from his 2013 album 'Crash My Party'.
Taking to the stage to collect the award for Entertainer of the Year, he said: "I have long sought to have one of these in my hands."
Kacey Musgraves, Little Big Town, Florida George Line, Mac McAnally, Dierks Bentley and Brett Eldredge were also recognised by the CMA's 6,000 members.

The full winners list is as follows:

Entertainer of the Year - Luke Bryan
Single of the Year - 'Automatic' by Miranda Lambert
Album of the Year - 'Platinum' by Miranda Lambert
Song of the Year - 'Follow Your Arrow' by Kacey Musgraves
Female Vocalist of the Year - Miranda Lambert
Male Vocalist of the Year - Blake Shelton
Vocal Group of the Year - Little Big Town
Vocal Duo of the Year - Florida Georgia Line
Musical Event of the Year - 'We Were Us' by Keith Urban feat. Miranda Lambert
Musician of the Year - Mac McAnally
Music Video of the Year - 'Drunk On A Plane' by Dierks Bentley
New Artist of the Year - Brett Eldredge

Cheryl Fernandez-Versini says people are "so ignorant" about her new surname.
The 'I Don't Care' hitmaker - whose maiden name is Tweedy - swapped her ex-husband Ashley Cole's surname for new husband Jean-Bernard Fernandez-Versini's moniker earlier this year but claims she hasn't had much support.
She said: "It's come quite naturally, you know. People are so ignorant, they just start calling us Cheryl, but I'll take that, whatever."
The brunette beauty also commented on fellow 'X Factor' judge Simon Cowell's claim that she only married someone with a hard to pronounce surname so that she could become a one name pop star, like Cher or Seal.
Cheryl hit back: "Yeah on purpose, so I Could be like Madonna? See how his brain works. I mean, who even thinks like that?"
The 31-year-old star also opened up about her two year break from the music industry, explaining that she needed time to get her passion back after her dramatic split from Ashley and her sacking from the 'X Factor USA'.
She told the December issue of Marie Claire magazine: "Honest. My gut instinct was like, 'It's enough'. For the first time since I wanted to be a pop star, I didn't have any fire in my belly.
"Without realising it, I had gone to a dark place, I needed to have a reality check and get some real feelings back."