Justin Bieber Surprises Selena Gomez Onstage (VIDEO)

Fans at Selena Gomez‘s show Sunday night at the Pacific Amphitheatre in Costa Mesa, Calif. certainly got their money’s worth! While onstage in an adorable sparkly pink dress, SelGo was greeted by a special, yellow-shirted visitor named Justin Bieber! The 17-year-old heartthrob greeted his girlfriend with a hug before beginning to sing “Favorite Girl.”

But that’s not all he sang!

Justin Biebs also sang a hit from Mr. J.T., Justin Timberlake! Check out SelGo’s guy covering “Cry Me a River.”

Following the show, Justin wrote of his gal’s performance, tweeting:

“@selenagomez u did great tonight. proud of u.”

Selena turned 19 on Friday and probably spent the weekend with her beau celebrating. What do you think of this hot teen couple?