TV talent show winner Connie Fisher has pledged she will be "solid as a rock" when she stars in the new West End version of The Sound of Music.
Show host Graham Norton with Connie moments after her triumph
The 23-year-old from Pembrokeshire said she felt she had "woken up on another planet" after her victory in BBC One's How Do You Solve a Problem Like Maria?
She will begin rehearsals in a week for Andrew Lloyd Webber's production.
As celebrations continued back home in and around Haverfordwest, her mother Jan said: "She's got what it takes".
An average 7.7m viewers watched the result on Saturday night, and most of the 2m who voted backed Connie against Helena Blackman, also 23, from Southampton.
Just before the result was announced Lloyd Webber revealed that Connie was his choice to play the nun who becomes governess to the unruly Von Trapp children, played by Julie Andrews in the 1965 film.
Connie told BBC Radio Wales: "I cannot believe it. It's like I've woken up on a different planet.
"Helena put up such a fight, didn't she? She's come from strength to strength and I thought there was no way in a million years I was going to win it.
"I always hoped that people would see Maria in me, because I've always been told, 'You're such a Maria'.
"Some people have told me, 'If there is one role for you it is Maria Von Trapp,' so here I am.
'Rejection after rejection'
"I've grown up with it. My favourite musical films when I was younger were The Sound of Music and Mary Poppins. I was a big Julie Andrews fan and there's always been a bit of Julie in me."
A Welsh-speaker, her first acting experience was in the youth section of the Torch Theatre at Milford Haven, and she sang at school and in the eisteddfod.
She graduated with first class honours from the Mountview Academy of Theatre Arts in Wood Green, London.
But she spent 18 months auditioning for roles with no success while working in a call centre.
She will now take on the huge role only months after landing her first professional job in the Torch Theatre's version of Aladdin last Christmas.
"After a year-and-a-half of rejection after rejection in auditions I thought it's been leading up to something," she said.
She referred to Martine McCutcheon's unhappy experience five years ago in the West End version of My Fair Lady, when the former EastEnders star quit after eight months because of health problems.
"I promise the public when they come to see me they will not have a Martine McCutcheon. I will be as solid as a rock and I will not let them down."
'Proud of my roots'
Rehearsals for he musical which opens at the London Palladium on 14 November begin in a week.
Connie told BBC Breakfast the reality of what has happened to her was only just sinking in.
"We drove past a billboard this morning. It was like' I'm on a billboard'. My life has gone mad. I'm loving it."
Connie will perform probably six performances of The Sound of the Music with another singer/actress taking on the role for the remaining two shows.
The show's producers Andrew Lloyd Webber and David Ian have both defended the practice of a "substitute" singer as a normal practice in musical theatre.
Connie said it was perfectly normal to have an alternate performer and stressed she was looking on this as her big chance.
She said: "I want a career in musical theatre not just five minutes of fame.
"I really want it to be a success and I'm going to give it my all."
Delighted: Connie's gran Dorothy Pare and mother Jan Fisher
Her mother, Jan Fisher, 58 and grandmother Dorothy Pare, 83, were in the audience to see her triumph.
Mrs Fisher said she was dumbstruck but always felt her daughter would make it.
"At the bottom of our hearts we knew," she said.
While Connie is poised for fame and fortune, her mother and grandmother are also finding themselves in the spotlight. They returned to their central London hotel in the early hours of Sunday to find the manager had sent up a bottle of champagne.
As Connie's mother and grandmother prepared to head home to Pembrokeshire for the celebrations, Mrs Fisher said: "There's going to be a few bottles of champagne around.
"I'm just really proud of my daughter who has worked so hard for what she's got.
"I just know she won't let you down. She's worked so hard for this.
"She's got what it takes. You can have what it takes, but it's what you do with it."