OTTAWA, Ontario — In a startling ending to a Davis Cup match, Canada lost to Britain on Sunday when a 17-year-old player, frustrated by missing an easy shot, suddenly launched a spare ball that hit the chair umpire in the left eye.

Britain advanced to the World Group quarterfinals with Kyle Edmund’s 6-3, 6-4, 2-1 default victory over Denis Shapovalov in the decisive fifth match.

Shapovalov had just been broken by Edmund, hitting wide on a simple backhand, when he took a ball out of his pocket and wildly smacked it.

The ball struck umpire Arnaud Gabas of France in the face, and the contact resulted in an automatic default. Gabas put ice under his eye as swelling and bruising began and was taken to Ottawa General Hospital for a precautionary evaluation.

Shapovalov immediately came over to check on Gabas after the accident and appeared to be shaken, holding his head in a towel.

“Obviously this is unacceptable behavior from me,” Shapovalov said. “I just feel awful for letting my team down, for letting my country down, for acting a way that I would never want to act.”

“I can promise that’s the last time I will do anything like that,” he said.

The crowd of 7,497 at TD Place was stunned by the turn of events. Team Canada captain Martin Laurendeau had never dealt with a similar situation.