Critics have yet to deliver their verdict, but Keira Knightley's West End debut last night met rave reviews from the audience.

First Knightley: Kiera signs autographs at the Comedy Theatre, where she appeared to have confounded critics who said she would struggle on stage

The British star, more used to Hollywood blockbusters, who plays an American socialite in the updated version of Molière's The Misanthrope at the Comedy Theatre, appeared to have confounded cynics who said she would struggle on stage.

While the official “first night” is not until next week, Knightley's opening performance treading the boards was “wonderful” according to members of the 800-strong audience.

In pictures: Behind the scenes at The Misanthrope

The show took more than £1 million in ticket sales in four days on the strength of Knightley's casting, which is alongside another A-lister, Damian Lewis, the British star of Band of Brothers. Knightley joins stars such as Cate Blanchett, Sienna Miller and Nicole Kidman in making the move from screen to stage.

“Keira was extremely good,” said Dee Jeffery, 48, an interior designer from Fulham. “I thought she was even better than Damian Lewis, which was a real surprise to me. She did a wonderful job.”

Melanie Hamelle, 33, a marketing director from south London, said: “She was amazing. We're so used to seeing American actors come to the West End and pretend to be British and it's more unusual to see a Brit doing an American accent — but she did it brilliantly.

“She was so confident throughout the whole performance. I didn't come specifically to see Keira perform but I've been a big fan for a long time and she didn't disappoint.”

Some said they had expected Knightley to struggle: “You never know what you are going to get when you go to a play starring a big movie star,” said Joan Jove, 30, a property developer from Pimlico. “Theatre is so different and sometimes they get it wrong, but Keira was expressive and I think she really worked in the role.

“People have obviously said before the performance that she would not do very well but clearly she can handle all that pressure and did a really good job on the night.”

Martin Kercher, a 33-year-old consultant from Surrey, said: “I was surprised by just how good Keira Knightley actually was. She was incredibly confident and carried off the performance very well.” Like some others, he was less impressed with her co-star: “Damian Lewis didn't play a drunk very well.”

Not everyone was convinced. Robert Erickson, 56, from Washington DC, said: “She was nothing more than an average actress. I wasn't impressed by her at all.” He added: “Frankly the acting during the play was mostly good, but the script was horrible.

“It just didn't translate from the original Molière script to the modern-language version.”

In pictures: Behind the scenes at The Misanthrope