Felix Auger-Aliassime moved into the third round of the Rogers Cup after countryman Milos Raonic was forced to retire from their all-Canadian matchup for medical reasons Wednesday night in Montreal.
After losing the first set 6-3, Raonic got his back worked on by a trainer midway through the second.
The 28-year-old from Thornhill battled to take that set by the same score, but after speaking with a doctor he shook hands with Auger-Aliassime in front of a disappointed crowd at IGA Stadium.
Ranked No. 21 in the world, Auger-Aliassime picked up his 30th win of the season and improved to 14-4 over his last five tournaments.
Aliassime broke Raonic in the fourth game of the first set to go up 3-1. But Raonic, the top-ranked Canuck at No. 19, returned the favour in the second set when he broke the teenager for a 3-1 edge.
In the only other match involving Canadians, Denis Shapovalov of Richmond Hill, fell to No. 2 seed Dominic Thiem of Austria 6-4, 3-6, 6-3.
On the women's side, Canadian Bianca Andreescu withstood a marathon match to advance to the third round.