Top seeds Rafael Nadal and Roger Federer showed their superiority en route to the ATP Rogers Cup round of 16, while Kei Nishikori and Milos Raonic were high-profile casualties.
French Open titleholder Nadal - the number one seed in Montreal - was a class above in his straight-sets win over Borna Coric on Wednesday.
Wimbledon champion and second seed Federer also eased past Peter Polansky in his first match since lifting the trophy at the All England Club.
Japanese fifth seed Nishikori failed to close out his second-round match against Gael Monfils as sixth seed and local hope Raonic also crashed out.
NADAL PUTS ON A SHOW
Relentless and dominant. That is the best way to describe Nadal's 6-1 6-2 win against Croatian youngster Coric.
The 15-time grand slam champion - winner of three Rogers Cup titles - made like work of Coric, who was worked all over the court.
"Never too easy," Nadal said. "At the beginning of the match there were great points. I think I started playing so well in the first set and in general, I played a great match. Last time that I played against him I lost, last year in Cincinnati. It was not an easy round for me."
Next up for Nadal is Denis Shapovalov after the 18-year-old defeated Juan Martin del Potro 6-3 7-6 (7-4) to become the youngest player to reach the last 16 at an ATP 1000 event since the Spaniard in 2004.
FEDERER PLEASED WITH AGGRESSION
There was little Polansky could do to stop Federer surging to victory in just 53 minutes in the opening match on Center Court, the Swiss rushing to the net and volleying brilliantly as he showed no signs of rust in his first match since winning Wimbledon.
"Overall, I'm very satisfied with the match. The conditions were tough here in Montreal. There was a lot of wind today and it was fast. Sometimes it's difficult to find the rhythm," said Federer, who triumphed 6-2 6-1.
"But I was happy that I was very focused on my service games. I was aggressive. This is how I want to play for the whole week. Anyway, it's a good start."
Federer will take on David Ferrer in the third round after the Spaniard defeated Jack Sock 7-6 (9-7) 3-6 6-1.
MONFILS THE MATCH-POINT SAVER, RAONIC STUNNED
Tension was high when Monfils and Nishikori entered a tie-break in the third set.
The Japanese looked sure to be the man to advance when he worked his way into a 6-2 lead, but Monfils pulled out a pair of astonishing forehands as he came back to draw level.
Another powerful shot from the baseline left Nishikori what might have been and set up a meeting with 12th seed Roberto Bautista Agut - a 7-5 6-2 victor over Ryan Harrison.
RAONIC SENT PACKING
Playing in his home country, it did not go according to plan for Raonic, who suffered a shock 6-4 6-4 loss to Adrian Mannarino.
Plagued by a wrist problem heading into his opening match, Raonic was swept aside by the Frenchman.
Canada's top dog is out.-- Tennis TV (@TennisTV) August 10, 2017
Adrian Mannarino is IN.
The Frenchman was on tonight. pic.twitter.com/GMYHC90ezj
Fellow seeds Jo-Wilfried Tsonga, David Goffin and Pablo Carreno Busta also lost, beaten by Sam Querrey, Chung Hyeon and Kevin Anderson respectively.
However, Alexander Zverev, Grigor Dimitrov and Nick Kyrgios progressed.