Justin Bieber And Selena Gomez Duet Onstage

Selena Gomez was the surprise guest at boyfriend Justin Bieber's show in Rio de Janeiro, Brazil last night (Thursday October 06).

Fans were treated to an unexpected performance by the star when she took to the stage to perform her track Who Says, which Justin joined her in performing towards the end of the song.

Biebs had previously dropped hints to fans that they could expect something special at the gig, tweeting:

"hearing [opening act] @CobraStarship killing it out there....almost time RIO....i got a big surprise tonight. #BRAZIL #myworldtour

After the show the Baby star went back on Twitter to thank Selena, writing:

"RIO!!! CRAZY!! thanks to @selenagomez for helping me do something special for the crowd. a duet never hurt nobody. WHO SAYS (sic)."

We wonder if Justin will return the favour when Selena hosts the MTV Europe Music Awards in Belfast on November 06... Keep it MTV to find out!

SEE MORE PICS OF SEL-IEBER IN OUR JB & SELENA GALLERY HERE!!!

WATCH OUR EXCLUSIVE JUSTIN BIEBER LIVE SESSION HERE