'What to Expect..' stars in London for UK premiere

The stars of the romantic comedy "What to Expect When You're Expecting" had plenty of praise for each other — and a warning about making out on the hood of a car — during the film's British premiere in London on Tuesday.

Cameron Diaz, Chace Crawford and Matthew Morrison, Anna Kendrick and Rodrigo Santoro were among the actors who walked the red carpet at the British Film Institute's IMAX theater.

The film — inspired by the bestselling book by Heidi Murkoff, and also featuring Jennifer Lopez, Dennis Quaid, Cheryl Cole and Chris Rock — looks at love through the eyes of five interconnected couples as they experience pregnancy and childbirth.

Kendrick and Crawford were one of the couples with some steamy moments in the film. But the reality wasn't quite that great, Kendrick said.

"The scene where we kind of make out on the hood of a car, it all looks pretty sexy and cool and fun, but I would not recommend trying to do that," she said. "It is uncomfortable. My legs were covered in bruises the next day. So I hope that it looks really nice, but it was actually quite a painful experience."

Director Kirk Jones gave high marks to Diaz, saying she was "phenomenal" in the scene where she gave birth.

"The concern as the director is always that you turn up on set, and an actress doesn't want to give her all because she'll be thinking, 'I don't want to look too sweaty, I don't want to look too red, you know, I don't want to really go for this,'" he said. "But she went for it, in a big way, yeah."

Diaz's onscreen partner Matthew Morrison also praised her, this time for her dancing skills.

"There's this one part where she wraps her legs around me, and I have to spin her around, and I said, 'Hold me tight because I don't want to, like, drop you and it's gonna help with me turning you around,'" he said. "And she squeezed me so hard I couldn't even breathe. It was, like, 'Damn it, let go, let go.' She's so strong, she's so strong."

Singer and former "X Factor" judge Cole takes on her first acting role in the movie as a judge in a celebrity dance-off contest.

Diaz gave her a thumbs-up, saying, "She played it beautifully, she was fun and entertaining and she provided a great energy for the set."

"What to Expect When You're Expecting" open in the U.K. on Friday.