Andrew Lloyd Webber’s new production of The Sound Of Music opens in the West End tonight.
Its star Connie Fisher will face the critics for the first time.
The former call centre worker won her role in BBC talent show How Do You Solve A Problem Like Maria?
Fisher, 23, will play the singing nun made famous by Julie Andrews in the 1965 film.
She will not be the only cast member suffering from opening-night nerves.
Leading man Alexander Hanson, 45, was hired only nine days ago to play Captain Von Trapp.
The original choice for the role, Peak Practice star Simon Shepherd, was replaced after two previews because his performance was “not working”.
Lloyd Webber’s £4m (€5.9m) production opens at the London Palladium.
The Rogers and Hammerstein show has already taken £10m (€14.8m) in advance ticket sales.
The production has not been without its problems.
Lloyd Webber came under fire for using a TV talent contest to find his leading lady.
Actress Emma Williams, who was to play Maria in alternate performances, quit in protest at her role being downgraded.
Fisher, from Pembrokeshire, Wales, is confident she can pull it off.
“I’ve trained for three years in musical theatre. I know I have the passion, commitment and stamina to perform eight shows a week and have always aspired to play the lead in a West End show,” she said.
“Audiences have always commented on my Julie Andrews-like qualities both on and off stage and I can’t think of a more suitable role. I have always dreamed of playing Maria.”
Hanson, who is taking on the biggest role of his career, said he was called two Sundays ago to be offered the role.
“I’ve been in high-pressure situations on stage, but this takes the biscuit, compressing five weeks of rehearsals into three days.
“I have run the gamut of emotions, from despair to: 'Well, I’ll give it my best shot,'” he told The Daily Telegraph.
Speaking about the moment he was offered the role, he added: “I had a hangover from my daughter’s 15th birthday party the night before and my first reaction was that this was ridiculous.
“I was on the verge of saying no when my wife walked into the room, overheard what was going on, and said very firmly: ‘School fees!’”