Those in attendance at the Pacific Amphitheatre in Costa Mesa, California on Sunday night enjoyed more than a fun set by feature act Selena Gomez.
They were also treated to a surprise performance by Justin Bieber, who hit the stage, gave his girlfriend a hug and then launched in an acoustic rendition of "Cry Me a River." Check it out here:
Justin later Tweeted about the experience: "Had a #greatnight and surprised the people. felt good to be on stage. nothing is changing that. #REAL. @selenagomez u did great tonight. proud of u."
Awww, so sweet! Let's not ignore Selena's efforts, either. Watch her sing on stage in the video below.