Spaniard was a dominant winner over Borna Coris in the Rogers Cup while there were also wins for Roger Federer and Grigor Dimitrov.
Rafael Nadal cruises in Montreal to take step closer to No 1 ranking
Rafael Nadal took a step closer to the No 1 ranking as he started his Rogers Cup campaign by overwhelming Borna Coric.
Nadal will overtake Andy Murray in top spot if he progresses to the semi-finals in Montreal this week.
And the top seed, who last topped the rankings in June 2014, quickly found his groove by dismantling his 20-year-old opponent 6-1, 6-2 to reach the last 16. The Spaniard was at his clinical best, taking four of the five break points he forced during the 71-minute contest.
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Roger Federer eased back into action for the first time since winning his eighth Wimbledon title last month as he also reached the third round with a dominant victory.
Federer, who celebrated his 36th birthday on Tuesday, took just 53 minutes to beat Canada's world No 116 Peter Polansky 6-2, 6-1. The Swiss star is seeking his third career title at the tournament, which he last won in 2006.
Fourth seed Alexander Zverev saved three match points - one of them after a 49-shot rally - before beating Richard Gasquet 6-3, 4-6, 7-6.
Canadian Milos Raonic suffered an early exit, the sixth seed losing 6-4, 6-4 to Adrien Mannarino, but 18-year-old wild card Denis Shapovalov gave the home crowd something to cheer.
Shapovalov, 143rd in the world, battled to a 6-3, 7-6 (7/4) success against former US Open champion Juan Martin del Potro and set up a clash with Nadal on Thursday.
Another man who battled back from the brink was Gael Monfils, who saved four match points in the deciding tie-break as he beat Kei Nishikori 6-7, 7-5, 7-6.
Eighth seed Jo-Wilfried Tsonga lost in three sets to Sam Querrey while ninth seed David Goffin is also heading home after going down 7-5, 6-3 to Hyeon Chung.
The other seeded casualties on Wednesday were Pablo Carreno Busta and Jack Sock, who lost to Kevin Anderson and David Ferrer respectively.
Grigor Dimitrov saw off Mischa Zverev in three sets while Nick Kyrgios dropped just five games in his victory against Paolo Lorenzi. Robin Haase saw off Ernesto Escobedo 6-4, 6-1 while Roberto Bautista Agut was a 7-5, 6-2 winner against Ryan Harrison.
* Press Association