We weren't going to report that Lindsay Lohan has a new enemy -- Michelle Trachtenberg -- because at this point, we've kinda lost count of L.Lo's rivals. But here's the skinny on that: Lindsay threw a hissy fit when she spotted Michelle at Miami Beach's Shore Club recently. "Those two hate each other, and Lindsay started screaming, 'Get her outta here,'" a source told Star. "She was threatening to get physical and actually fight Michelle." (Note: We had to take three curse words out of that mini-rant.) Lindsay ended up just leaving the club herself.

Now here's why we're so intrigued: Lindsay is currently hooking up with Pete Wentz, according to New York Daily News, which was what Michelle was doing over the summer. (Check the video below for some quick footage of Mich and Pete after watching The Academy Is… play at Warped Tour in July.)

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