George Clooney’s girlfriend Sarah Larson has opened up about her relationship with the Hollywood star, revealing he first seduced her years ago.

The couple has been dating for a year, supposedly after initially meeting at the Las Vegas premiere of Ocean's Thirteen in 2007, when Larson was working as a waitress.

But the 28-year-old has now confessed she first met Clooney at his birthday party in Sin City, several years earlier - when she was dating someone else.

Larson explains, "It was on his birthday three or four years ago at Whiskey at Green Valley Ranch (in Las Vegas).

"He was with his friends and I was with some friends. We were all dancing, taking pictures, being silly."

She claims Clooney then looked her up when he returned last June: "He heard I was working at Moon (nightclub). We hung out."

A month later they were dating.

A year on, Larson reveals she will be spending her beau's 47th birthday in May at his villa in Lake Como, Italy.

She tells the Las Vegas Review Journal: "We'll be in Como, which isn't that far from Milano."