Denis Shapovalov was left "incredibly ashamed and embarrassed" for letting Canada down by blasting a ball into the face of the chair umpire to hand Great Britain a place in the Davis Cup quarter-finals.
Arnaud Gabas was taken to Ottawa General Hospital for precautionary checks after teenager Shapovalov reacted to being broken in the third set by unleashing a forehand which struck the Frenchman, leaving him with a black eye.
Shapovalov was trailing 6-3 6-4 2-1 in the deciding rubber when referee Brian Earley defaulted the Wimbledon junior champion, who was horrified after unintentionally leaving the official with bruising.
The 17-year-old said: "I would like to begin with apologising to that umpire, the referee and to all ITF officials
"It was unacceptable behaviour from me. I feel incredibly ashamed and embarrassed, for letting my team down and my country down.
"That's the last time I'm going to do anything like that. I'm going to learn from it."
-- Davis Cup (@DavisCup) February 5, 2017
Vasek Pospisil defended his team-mate following his on-court misdemeanour.
He tweeted: "No one is nicer or carries themselves better for a 17 y/o than Shapovalov. Everyone can see that today was an accident. Can happen to anyone."