Actor Ewan McGregor has confessed that he found the choreography for his new West End show daunting when he turned up for his first day at work.
Jane Krakowski stars with Ewan McGregor in Guys and Dolls
McGregor, 34, is to star in Guys and Dolls, his first stage musical.
He said he was already concerned about the singing when he turned up for rehearsals and saw the dancing steps, calling them "full-on".
"But maybe it was the element of the musical that I considered the least beforehand," he added.
McGregor previously sang and danced alongside Nicole Kidman in his starring role in the film Moulin Rouge, but a West End run requires more training in the disciplines.
He has been taking singing lessons ahead of his role as gambler Sky Masterson in the revival of the 1950s musical.
On the singing, he said: "A lot of people were worrying me saying: `How's your voice?'.
"I could sense there was this kind of panic around me but I worried a lot less once we started. Your voice gets stronger and stronger."
He added: "You become incredibly aware of not damaging your vocal chords, you don't go to places that are too noisy, you don't go to noisy or smoky restaurants. You just take care of it."
McGregor returns to the stage after a five-year break.
He last trod the boards in the West End production of Little Malcolm and His Struggle Against The Eunuchs.
He said he would not be comparing his performance in Guys and Dolls to that of Marlon Brando, who starred in the big-screen version of the musical.
"I can assure you that I don't start thinking: `That's a bit like Brando, I mustn't do that.' You just try to find the character and see how it fits in your shoes."
Also starring in the show - which opens at London's Piccadilly Theatre on 1 June - are Jenna Russell, Douglas Hodge and Ally McBeal actress Jane Krakowski.