Selena Gomez's Surprise Stage Guest: Justin Bieber!

Staying busy over the weekend, Selena Gomez rolled into Costa Mesa, California for a gig at the Pacific Amphitheater last night (July 24).

The “Ramona & Beezus” babe looked fabulous as she took the stage in front of a packed house, singing all of her hits for her screaming fans.

And as an added bonus, Selena’s boyfriend Justin Bieber paid a surprise visit, singing “Favorite Girl” as well as Justin Timberlake’s “Cry Me A River.”

After the gig, Justin took to his Twitter page to share his excitement over Gomez’s concert. He tweeted, “@selenagomez u did great tonight. proud of u.”