In an Eerste Divisie soccer match from the Netherlands, FC Oss's Jochem Jansen was knocked out after being drilled in the face by a free kick from his teammate, captain Marcel van der Sloot.
Jansen was walking up the field to position himself for the free kick, but didn't get a chance to turn his head around before the ball took him out. Jansen was treated by medical staff and walked off the field under his own power, albeit a bit shaken.
Interestingly enough, Van der Sloot seemed to find his teammate's misfortune mildly amusing. However, we don't think he would like it too much if the roles were reversed.
H/T DT.