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Justin Bieber is the 10-year-old girl crush equivalent to the 16-45 year-old girl crush power that Robert Pattinson has. When Justin walked onstage at the Z100 Jingle Ball concert on Friday night, you couldn’t hear a thing except for a massive high-pitched shriek.

John Mayer was introduced by Peter Facinelli, who also elicited screams from the crowd as well. He requested the crowd quiet down so he could make his introduction.

Taylor Swift appeared a few times throughout the evening, and ended her night alongside John Mayer for their collaboration, “Half of My Heart,” off his new Battle Studies album. Left alone onstage, Mayer then busted into a cover of Cream’s blues-rock classic, “Crossroads,” which seemed to confound the audience, who headed en masse for a strategically timed bathroom break.

“I’m John Mayer, I’m 52 years old,” he laughed afterwards. “Get the old dude off the stage and get Justin Bieber on here!”

Then came Justin Bieber. Watch the video of Justin and Jordin Sparks performing ‘No Air’ after the jump.

Gallery Info: Taylor Swift, Justin Bieber, Usher, Orianthi, John Mayer, Peter Facinelli, Jordin Sparks, Jay Sean, The Fray, Alisson Iraheta, Kris Allen, Pitbull, Ke$ha, Boys Like Girls and Miranda Cosgrove performing at the 2009 Z100 Jingle Bell Concert on November 12, 2009.