The 17-year-old Bieber made a surprise visit on stage during Selena’s concert in Orange County last night to help celebrate her 19th birthday.
The Bieb’s took the stage during her acoustic set and belted out Justin Timberlake’s famous breakup song “Cry Me a River”.
Selena looked totally surprised but we suspect she had a good idea that something was going to happen during the show.
Watch Justin Sing "Cry Me A River" During Gomez's Birthday Concert
The only issue we would take on the surprise visit is that “Cry Me a River” is a song about breaking up a relationship – not celebrating one.
We hope Justin doesn’t know something we don’t yet.
But we think it was a perfectly innocent birthday gesture and taken at face value is actually a very romantic thing to do for his girlfriend.
Selena is currently performing concerts on tour with her band “Selena Gomez and the Scene” and promoting her new album “When the Sun Goes Down” featuring her hit single “Who Says”.
She also is starring in the recently released movie “Monte Carlo”, a comedy about three young women vacationing in Paris who find themselves whisked away to Monte Carlo after one of the girls is mistaken for a British heiress.
Gomez can also be seen this November in the comedy “The Muppets” starring alongside Mila Kunis, Emily Blunt, Neil Patrick Harris, Neil Patrick Harris, Jason Segel, and Amy Adams.
Watch Selena Gomez in “The Muppets” Movie Trailer
Justin Bieber has just completed a month long vacation and is now back in the studio working on his new album due out later this year.
Related: Justin Bieber talks about his new album – Video
Bieber will also start filming his basketball movie this summer with pal Mark Wahlberg with an expected release date in 2012.
Wahlberg says neither him nor Bieber will be singing or dancing in the movie, and it will be a good chance for Justin to bring his dramatic acting skills to the table.
The movie is being produced by Wahlberg, Stephen Levinson, and Bieber’s manager Scott “Scooter” Braun.
Ah, to be young and in love – and have friends in high places.
Follow @InfoStar on Twitter