In the 3rd set of the deciding rubber of the Davis Cup match between GB and Canada, 17 year old Shapovalov smacked the ball out of play in frustration after a missed backhand gave Edmund the break to go 2-1 up in games, and already 2 sets up.
Only, the ball didn't go out of play. It hit the umpire square in the face, leading to the match and Davis Cup tie being defaulted to Great Britain.
Woops.
At 6:01.