Larson used to date George Clooney and reportedly met him when serving him onion rings at the movie premiere for Ocean's 13. She's also known as the woman who broke her foot in a motorcycle accident while riding with the world's most famous bachelor.
Clarke said his sources spoke with Urlacher and Larson while they were holding hands on a Valentine's Day date at a Bellagio nightclub called The Bank.
Clarke said that was the only sighting of the pair but that he's "expecting to hear more because it was quite a shocker."
"We know that he's sort of Mr. Romance when he gets to Las Vegas. I broke the story about 5 1/2 years ago of him walking out of the same club -- it's changed its name -- but she (Paris Hilton) was riding him piggyback and had a broken stiletto on her heel and they flew back to Chicago that morning and it created quite a stir," Clarke said.
According to Clarke, Larson and Clooney were in Vegas over Valentine's Day weekend last year and "painted the town red.
Urlacher's most recent relationship news has had more to do with the custody battle with his ex-girlfriend Tyna Robertson and their son.