Four-times champion Novak Djokovic has advanced to the third round of the Canadian Open with a routine victory over local wild card Peter Polansky.

Djokovic, coming off his fourth Wimbledon title last month, fired seven aces and never faced a break point in the 6-3 6-4 encounter.

Heavy morning rain delayed the match by about an hour with the ninth-seeded Serb needing one hour and 24 minutes to seal his place in the last 16.

Earlier on Wednesday, tournament officials announced that Argentine world No.4 Juan Martin del Potro had withdrawn with a left wrist injury.

“Sorry to my fans in Toronto but I have to pull out of the tournament since my left wrist needs some days of rest,” Del Potro tweeted.

Del Potro, who had a bye in the first round, was set to play Robin Haase with the Dutchman instead facing lucly loser Mikhail Youzhny.

The Russian veteran ws no match for Haase who won his way into the hird round 7-5 6-2.

Karen Khachanov upset 12th-seeded Spaniard Pablo Carreno Busta 6-4 7-6 (7-3) while Ilya Ivashka overcame Ryan Harrison 7-6 (7-5) 6-4 in a battle of qualifiers.

Bulgarian fifth seed Grigor Dimitrov and Croatian Marin Cilic progressed to the round of 16 late on Tuesday while a host of second-round encounters were interrupted by more rain on Wednesday.

Those forced of the court include Austrian seventh seed Dominic Thiem, who was a set down to Greek youngster Stefanos Tsitsipas, and Canada’s former world No.3 Milos Raonic, who was trailing American Frances Tiafoe by a set.

Top seed Rafael Nadal is scheduled to play his opening match of the tournament against Benoit Paire in the evening session.