Strictly's Kym Marsh reportedly suffered a panic attack and had to be consoled by cast and crews during rehearsals.
The Coronation Street star, 46, burst into tears and the session was bought to a finish, it is understood.
Kym and her pro partner Graziano Pernice were practising their quickstep to Sweet's Ballroom Blitz, which closed Strictly's BBC themed episode two weeks ago.
The dance landed her in the bottom two of the leaderboard and judge Anton Du Beke told her the performance lacked her usual confidence.
The TV presenter was saved by the public vote however, and their Halloween dance scored much higher on Saturday night, landing her in third place on the board.
The Sun reports that during rehearsal, Kym struggled to continue dancing as producers attempted to lessen her anxiety.
An onlooker said: “She was very upset she just couldn’t stop crying and hyperventilating.
“In the end there was no choice but to stop rehearsals.”
Sources added there was concern Kym would not be able to go on, but she went on to dance in the live show that evening.
A friend told The Sun: “Kym doesn’t mind admitting she suffers from anxiety and panic attacks.
“That sort of thing can catch her out.”
Speaking after their quickstep to Strictly host Claudia, Kym thanked the cast for their support.
She said: "I felt pretty confident going in...I've had a bit of a dodgy day when it comes to confidence, but the team and everyone here has just picked me up. I can't thank you all enough for that."
Appearing on Strictly spin-off It Takes Two, Kym spoke further about the dance and day beforehand.
She told presenter Janette Manrara: "We had so much fun, after having a day of a bit of a meltdown, I just got on there and thought, do you know what, let's just have fun? And we did, we just went out and just enjoyed ourselves."
Kym and Graziano's friendship is delighting viewers, and the actress has admitted he has become like "her little brother".
“Graziano is from a big family himself and is very family-orientated so it was important for us to build a friendship and I wanted to integrate him into the family.
"He’s fit in really well. Everyone loves him," she told Hello magazine.
Graziano added that he too feels like part of Kym's family, revealing the Corrie star invites him home where she prepares Italian food with her brood, making him feel "so welcome".
“At the end of the day, when we’ve finished the rehearsals, I’ll be in my hotel on my own. But Kym knows that, so she invites me back," he explained.
Kym has three kids David, 27, Emilie, 24 and Polly, 11 and is married to Scott Ratcliff.
Graziano, meanwhile, married Gina Lini is Sicily this year after delaying their wedding due to Covid.
The Mirror has approached Kym's reps for comment.
The BBC declined to comment when approached.
