We all know by now that Justin Bieber has very high expectations of what he expects from his fans' behaviour - i.e. don't scream too loudly, don't talk when he's talking, don't ask him for a picture on his day off. Or at all, for that matter.
However, it seems that the Canadian pop star has reacted in the most aggressive manner yet to a fan in Barcelona who touched him through the window of his car when either arriving or departing from the venue last night.
TMZ has footage of Bieber driving past a group of fans, the window of his car rolled down, as an excited fan reaches in through the window to touch him. He reacts by striking the fan in the face - hard enough to make him bleed - eliciting shocked gasps from the crowd.
On one hand, we can kind of see it from his side; the fan could have had a weapon of some sort. On the other hand, he clearly had an open palm and y'know, if you don't want that to happen, maybe don't drive by a group of your fans with your window rolled all the way down...
See for yourself below: