Did Justin Timberlake cheat on Jessica Biel with Olivia Munn? That’s what Us Weekly would like us to believe. Once a year, UsWeekly decided to stir up some drama between Timberlake and Biel – in the form of accusing JT of cheating. Last year it was Rihanna, remember?

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2010′s flavor of the year is new Daily Show correspondent Olivia Munn. According to the magazine, the pair met at some MySpace networking event and then shared some steamy nights together in a hotel room.

“After exchanging numbers, he “started chasing her immediately,” says an insider.

Munn resisted his advances, telling him it was a no-go if he was still with Biel, 28, the source tells Us Weekly. But Timberlake “has been telling people it’s over with Jessica, even though “the reality is he’s just doing it behind her back.”

Believing he had left Biel and that her relationship with Timberlake might develop into something serious, Munn took him to her hotel, the Gansevoort Park Avenue NYC, Sept. 27 and 28, where “they were openly affectionate,” the insider adds.

The insider tells Us the two “had amazing sex” that night.

Amazing sex? I guess I can see that. He did bring sexy back, afterall. Do you think he and Biel have an open relationship?

Photos: Fame

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