Robert Pattinson sweated like a ''crazy person'' while filming intimate scenes with Julianne Moore.

The 28-year-old actor - who stars alongside the actress in the new drama 'Maps to the Stars' - struggled to keep his cool on set in Toronto, Canada, during a raunchy sex scene with the flame-haired beauty.

The 'Twilight' star began sweating so profusely that the 53-year-old actress even became concerned for his health.

He told Heat magazine: ''That was kind of hilarious - it was the first time I'd met Julianne as well. It was so hot in Toronto and she's one of these people - she doesn't sweat at all! But I sweat like a f**king crazy person. And I was trying to literally catch drops of sweat to stop them hitting her back.

''Afterwards, she was like, 'Are you having a panic attack?' It was so embarrassing.''

Meanwhile, Robert also admitted he worried he wouldn't make it in the industry after failing to land any roles for three years when he first moved to Los Angeles.

He explained: ''I'd been in LA for three years and not got a job, ever. 'Twilight' was my first job with my American agent, who had a six month turnover rate with clients.

''If you hadn't got a job in six months, you were kicked out of the agency, and my agent really stuck out for me.''