Swiss 18-year-old Belinda Bencic secured her second career title by winning the Rogers Cup as Simona Halep retired hurt in the final.
Bencic, who beat Serena Williams in the semi-final, came through 7-6 (7-5) 6-7 (4-7) 3-0 in Toronto.
Second seed Halep required treatment as she struggled with a leg injury and the extreme heat.
The Romanian said: "Sorry that I couldn't finish the match. I tried very much but it wasn't possible."
Bencic, who accounted for four of the top six seeds this week - Halep, Williams, Caroline Wozniacki and Ana Ivanovic - said on BT Sport 2: "Even if I would have lost it would have been an amazing experience.