A waitress and a teacher were among five amateurs who wowed the audience at West End musical Chicago on Thursday after winning talent show Musicality.
The group received huge applause from the audience
"We're terribly proud of them. It's an amazingly gruelling challenge, and they really stepped up to that," said the show's spokesman, Andy Lock.
The five, who appeared in Chicago for one night only, were chosen from about 2,000 hopefuls on the Channel 4 show.
Waitress Rebecca Dent, 22, who played Roxie Hart, said: "It was electric."
"The audience were phenomenal, they were like a football crowd," she said after taking over Jennifer Ellison's role.
Primary school teacher Matthew Goodgame, 24, who played lawyer Billy Flynn, said: "It was the best night of my life apart from my wedding."
Rebecca Dent and Caroline Graham said they loved the performance
Times theatre critic Richard Morrison gave the performances five stars out of five.
"The achievement of the 22-year-old Lancashire lass Rebecca Dent... struck me as little less than sensational," he wrote in Friday's newspaper.
He also praised the other winners, Matthew Goodgame, box office assistant, mother of five Donna Hazelton, 40, plumber's assistant Warren Sollars, 20 and physiotherapist Caroline Graham, 23.
"As for Warren Sollars... I felt sorry for him: allocated bit parts here and there. But he shone where he could," he said.
He described Matthew Goodgame and Donna Hazelton as both having "warm, tuneful voices, and they visibly relished every minute".
He said Caroline Graham "started nervously in All That Jazz, but threw herself into the later dances with tremendous gusto."
The physiotherapist from Huddersfield said she enjoyed every minute.
"It was electric, better than I ever imagined it would be."
Ms Hazelton agreed: "You can't beat an adrenalin rush like that. It's just the most amazing feeling, and the response from the crowd was incredible."
Members of the audience included Jennifer Ellison and Gaby Roslin, who previously played Mama Morton in the jazz-era show which was turned into an Oscar-winning film starring Richard Gere, Rene Zellweger and Catherine Zeta Jones.
The five Musicality winners will also record a CD.
They were put through rigorous training by Chicago producers to prepare them for their professional debut.
Viewers will be able to see how the winners got on in Chicago in the final TV show on 1 December.