Keira Knightley stunned her 'Begin Again' co-stars with her singing skills.

The 29-year-old beauty plays a singer-songwriter in the movie and all her co-stars were full of anticipation for her first musical scenes - and were left pleasantly surprised.

Mark Ruffalo recalled: ''The tension was thick with anticipation and then she sang and everyone was like, 'Oh my God, she can sing.' ''

Meanwhile, another of the film's cast, James Corden, admitted they were shocked when they were able to shoot in New York's busy Times Square without attracting a huge crowd.

Speaking during a Q&A session at the Apple Store on Regent Street, London, he said: ''There was a great scene with Mark and Keira, which was shot in Times Square.

'With no permits, at 3am, one camera, about 10,000 tourists and Keira Knightley... and nobody noticed!''

During the fan meeting, Keira admitted she has her sights set on a ''really dark'' role next.

She said: ''I love sci-fi, I want to do a sci-fi that is really dark.''

Keira recently joked while she was pleased with her voice in the movie, she wanted to ''sound like Adele''.

She previously said: ''I had actually done it on one other movie but in a very different style, but no, I've never sung like this. I was actually quite disappointed that I didn't sound like Adele.

''You know when you're in the shower and you're just singing and you think, 'Wow, I sound really good right now. I sound so good I could totally do that Adele thing'. And then you get into a recording studio, as I did, and you think, 'Oh, no, I can't do the Adele thing'.''