Novak Djokovic breezes past Gilles Muller in Toronto

He took the match in straight sets, 7-5 7-6(3).

Djokovic, playing his first match since his shock third-round Wimbledon loss to American Sam Querrey, won 73 per cent of his service points and wrapped up the win in one hour and 43 minutes.

The Serbian world number one, a three-times winner of the Canadian Masters event, will next play Czech qualifier Radek Stepanek, a 7-6(5) 6-4 winner over Canadian wildcard Peter Polansky.

"It's tough playing the first hardcourt match since March. It was hot and that made the ball move very fast," said Djokovic. "It was hard to control, it was not easy to play. But I managed to stay tough."

Querrey, whose Wimbledon run came to an end with a quarter-finals loss to eventual runner-up Milos Raonic, could not pen a similar script as he retired from his second-round clash with Belgian seventh seed David Goffin while trailing 6-4 2-1.

Japanese third seed Kei Nishikori beat American qualifier Dennis Novikov 6-4 7-5 while ninth seed John Isner fell 7-6(3) 6-7(4) 6-4 to American Ryan Harrison.

Grigor Dimitrov (Bulgaria) beat Denis Shapovalov (Canada) 6-4 6-3

4-Milos Raonic (Canada) beat Lu Yen-Hsun (Taiwan) 6-3 6-3

Jared Donaldson (US) beat Fabio Fognini (Italy) 6-3 3-6 6-3

Ivo Karlovic (Croatia) beat 8-Marin Cilic (Croatia) 6-4 7-6(3)

16-Jack Sock (US) beat Donald Young (US) 6-4 6-3

1-Novak Djokovic (Serbia) beat Gilles Muller (Luxembourg) 7-5 7-6(3)

12-Bernard Tomic (Australia) beat Steven Diez (Canada) 6-3 7-6(4)

Kevin Anderson (South Africa) beat 6-Dominic Thiem (Austria) 4-1 (Thiem retired)

7-David Goffin (Belgium) beat Sam Querrey (US) 6-4 2-1 (Querrey retired)

Ryan Harrison (US) beat 9-John Isner (US) 7-6(3) 6-7(4) 6-4

Rajeev Ram (US) beat 13-Lucas Pouille (France) 6-4 7-6(5)

Radek Stepanek (Czech Republic) beat Peter Polansky (Canada) 7-6(5) 6-4

3-Kei Nishikori (Japan) beat Dennis Novikov (US) 6-4 7-5

10-Gael Monfils (France) beat Vasek Pospisil (Canada) 7-6(6) 6-0