Justin Bieber apparently punched a man when he reached into the pop star's car in Barcelona.
Video footage shows Bieber, 22, lash out at the man who tried to touch him through his moving vehicle's open window.
The man then turns to the camera to reveal he has a bloody mouth, in footage posted online by celebrity news website TMZ.
Bieber had performed in the Spanish city on Tuesday night as part of the European leg of his Purpose world tour.
Last month the Canadian star stormed off stage during a concert in Manchester after complaining about his "screaming" fans.
After leaving the stage, he returned to continue his performance, saying he was "going to quit talking" for the rest of the night.
During his UK tour in 2013, Bieber burst out of a vehicle and lunged at a photographer in an incident which was also caught on camera.
A representative for Bieber could not be immediately reached.