Justin Bieber Surprises Fans at Selena Gomez' Concert

Justin Bieber treated fans to a surprise performance at his girlfriend Selena Gomez's first We Own the Night concert last weekend in California. After giving Selena a big hug, the Biebs sang his "Favorite Girl" and then Justin Timberlake’s "Cry Me A River." Now that we're done with the concert cameo, how about a live duet?
(via MTV and Just So You Know)