Jude Law in London Nov. 18
has a few words of advice for Matt Damon
, PEOPLE's 2007 Sexiest Man Alive
"Keep up the good work, Matt," Law said of his co-star in The Talented Mr. Ripley
, at Sunday night's London premiere of his new film Sleuth.
Law, a former Sexiest Man Alive title-holder
, told PEOPLE that the choice of Damon, 37, was "cool" and laughed as he disclosed that wearing the crown was "not particularly" hard work.
The 34-year-old flew to London especially for Sunday's premiere: Law said he needed to be in Toronto the following morning to resume filming Repossession Mambo
The film also is the reason Law snipped off his golden locks. Michael Caine, who also stars in Sleuth,
jokingly told PEOPLE: "You won't recognize him with the haircut."
For Law's part, he appeared to enjoy his new low-maintenance 'do. "It's very easy like this, I have to say," Law told reporters, patting his short, clipped hair.
His hair wasn't the only thing to change. Law looked exceedingly fit and admitted that he had been working out for his new film. His fitness regime is "quite intense," he said.