Justin Bieber Wins Big at AMA's

It was a big night for Justin Bieber, who took home four American Music Awards, even beating his mentor, Usher, for Favorite Pop Rock Male and also won Artist of the Year.

At 16, he's the youngest to ever win the award. Usher actually came up on stage to give his prodigé a bear hug.

And that other teen sensation, Miley Cyrus, ruled the red carpet at the Nokia theater in Los Angeles, wearing a Marchesa mini dress with a dramatic train.

Taylor Swift caused double-takes when she debuted her new "do," straight hair and bangs!

And Rihanna wowed in a peekabo gown before opening the show looking sexier than ever.

The show was jam-packed with elaborate performances that brought the star-studded crowd to its feet.

The grand finale? A collaboration between former boy band rivals, the Back Street Boys and New Kids on the Block. The guys may look a little older, but they still make the girls scream.

Other artists who were multiple winners were Eminem and Usher.