tennis/omnium-canada/story">
Gael Monfils was forced to retire from the game following a tough-to-watch injury.
As he jumped to return a ball, the Frenchman landed badly on his feet and his ankle took the hit.
After writhing in pain on the pitch, Monfils made the decision to retire.
Jack Draper moves on to the next round.
Watch the sequence in question in the video above.
