A tipsy Kristin Cavallari, 23, got into an early morning screaming match with a gorgeous brunette who was flirting with her ex Brody Jenner, 26, at the Nylon Young Hollywood party at the Roosevelt Hotel in Hollywood Wednesday night.
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Cavallari had been fuming since 10:20 p.m., when she spotted Jenner hitting on Hills co-star Audrina Patridge, 25, who didn't seem interested as she's dating Ryan Cabrera, 27.
Jenner stopped speaking to Patridge to try to calm down Cavallari, who was on her second beer, but she grabbed his arm angrily before they parted.
VIDEO: Kristin attacks Stephanie Pratt
At midnight, Cavallari stood up quickly with her dress hiked to her waist -- flashing a pair of white mesh panties! She didn't seem too concerned, and pulled her dress back down. (Joked Cavallari's trainer John Damon to some pals, "See that sick body? That's because of me. I torment her on the treadmill!")
A few minutes later, a gorgeous brunette began chatting up Jenner, making Cavallari -- who gave the girl an icy hello -- increasingly annoyed. Cavallari, who had been drinking all night, threw a cell phone she'd received for free from a swag suite down on the floor in anger.
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After about 30 minutes of Jenner's flirtation with the brunette, Cavallari approached her and began screaming as a Hills producer whispered into his microphone, "This is going to get ugly." The brunette's blonde friend also began yelling back at Cavallari.
Jenner intervened after about five minutes of fighting, pulling Cavallari away and giving her a hug. Cavallari smiled and flashed Jenner a hotel room key and the two of them -- with their arms all over each other -- took off together.
Jenner and Cavallari haven't dated since 2006, but have always had sexual tension. In an October episode of The Hills, Jenner's then-girlfriend Jayde Nicole demanded he choose one of them, and he admitted he "didn't know" if he had feelings for Cavallari.
For more juicy Hills gossip -- including which castmate Cavallari secretly "hates" and the dangerous ways Spencer Pratt has "brainwashed" his wife, Heidi -- pick up the new issue of Us Weekly, on stands now.
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