After checking out a Cirque du Soleil show at Treasure Island with four pals , Spears hit The Hard Rock Café, where 50 Cent was throwing a huge party. After the pop star found a VIP booth with Diddy, 37, and Hilton, 26, the DJ shouted out, “Give it up for Britney Spears!�? and the crowd erupted in cheers.

After Hilton made her way to another club , Spears followed Diddy over to Tao at 1:30 am, where the two chilled in a corner booth. “She was dancing and having a good time with Diddy all night,�? says an eyewitness, who spotted the mom of two enjoying cocktails with her rapper pal at club Jet after 2am. “She was drinking and letting off steam.�?

Two hours after leaving the club, Spears was spotted heading to Diddy’s suite at the Palms Hotel Fantasy Tower with two gal pals.