Justin Timberlake has said he needed special running training for his role in science-fiction thriller In Time.
The singer-turned-actor, 30, joked he had never done so much running before playing Will Salas, who struggles to stay alive after waking up with only 23 hours to live in Andrew Niccol's futuristic film.
"I had to specifically train and do some running to train for the movie," the Hollywood heartthrob said at the film's UK premiere in London's West End.
But Justin didn't mind putting in the hours of hard work.
"This is the first character I have played that I really admire a lot. He is brave and I hope I would come out swinging too," he added.
JT was joined by co-stars Amanda Seyfried, who braved the chilly weather in a blue suit jacket and skimpy shorts by high street chain H&M, and Cillian Murphy.
The film is set in a futuristic world where time is the new currency.
"I think it's an intriguing concept for a movie. I don't know if it would work in real life but I think the best sci-fi films have a way of taking other-worldly concepts and throw some metaphors at us," continued Justin.
Amanda, 25, had only high praise for her partner-in-crime after he gave her a helping hand on set - literally.
"He saved my life while I was running in six-inch YSL heels," she revealed.