Referee Armando Villarreal was hit by an object—thought to be a bottle of water—thrown from the crowd as he went to check video replays during Atlanta United's clash with Minnesota United on Tuesday.
Minnesota were 1-0 up with nearly an hour played at Mercedes-Benz Stadium when goalkeeper Kyle Reynish came charging out of his area and caught Abu Danladi.
Villarreal then went over to check the replay to determine what action should be taken when an object came flying out of the crowd and struck him on the head.
The incident was captured on Twitter:
Atlanta Journal Constitution reporter Doug Roberson said the official had been hit by a bottle of water:
Villarreal did not appear to be injured and continued with his duties, awarding Minnesota a free kick on the edge of the area and handing Reynish a red card.
According to Matt Reed at NBC Sports Soccer, the referee's decision was the right one:
Reynish's dismissal saw Atlanta send on fourth-choice goalkeeper Alexandros Tabakis for the final 30 minutes in an exciting game.
The hosts then recovered to go 2-1 up before two late goals from Minnesota saw them claim a dramatic victory, with Kevin Molino scoring the winner in the 96th minute.
Per Roberson, Atlanta coach Gerardo Martino was critical of the officials after the game and said it was obvious Reynish's foul was a red card but that other decisions had been missed.
It could be a costly match for Atlanta. Not only did they lose the game and their goalkeeper, but they may face further punishment over the object thrown from the crowd.