Kimora Lee Simmons Gets Steamy with Usher in Vegas, Kim K & Khloe Watch

Kimora Lee Simmons was in Usher's sights this weekend -- which quickly turned into a steamy encounter ... all caught on video by Kim K while in the company of Khloe too.

The three gals were in Vegas Saturday to watch the singer perform, and once again ... Kim snagged great seats. This time, however, it seemed to be a ladies' night ... and KLS was the one Usher focused on with a lot of care and tenderness.

As you can see, the guy was shirtless and in search of some body rubs ... which Kimora provided. He even got her up on her feet and held her close as he serenaded her -- and the kicker ... he eventually fed her a strawberry in a very sensual fashion.

BTW, the attention Kimora's receiving here makes sense -- she played Usher's love interest in the music video for "Nice & Slow" way back in 1998. So this is like a reunion of sorts.

Looks like Khloe might've gotten a feel or two as well -- meanwhile, Kim just stood back and filmed ... seems she didn't really want any part of it.

More for Kimora, as it turned out ... 'cause she had Usher all to herself for several minutes. The irony, of course, is that both Kim and (maybe) Khloe are the ones who are very publicly single ... and yet, neither of them dove in for a taste of Mr. Raymond. Kimora is still technically married -- although she's estranged from her husband, so no harm/no foul.