World No.1 Roger Federer exited the Rogers Cup on Thursday, while Wimbledon champion Rafael Nadal continued his remarkable run.
Top seed Federer opened play and all appeared normal early on but unseeded Frenchman Gilles Simon turned things around for a stunning 2-6 7-5 6-4 triumph.
Nadal, meanwhile, claimed a comfortable 6-4 6-2 victory over American qualifier Jesse Levine.
Federer, who was playing his first match since losing to Nadal at Wimbledon, is having a poor year by his standards and lost his 10th contest out of 53 this season, where he has won two titles and no Grand Slam championships.
Of course, the rapid emergence of Nadal, who has beaten Federer in all four contests between the two in finals this season, has played a significant role in the 26-year-old's downturn.
This particular venue had been a favourite of Federer's, however, as he was unbeaten in 13 matches at the Rexall Centre, claiming titles in 2004 and 2006.
But Federer, who has 55 career titles, will have to wait until next year to try and become the third player in the Open era to win three Canadian titles, joining Ivan Lendl (six) and Andre Agassi.
Simon is ranked No.22 in the world and won the event in Indianapolis on Monday.
Nadal was playing his first match since winning Wimbledon and rolled into the third round of this hardcourt event with a straight sets win over Levine.
The world No.2 since July 2005 has won his last four tournaments played and is on a 25-match winning streak.
"It's not easy to play, especially after Wimbledon. I didn't have much practice so it was a tough start," said Nadal, who became first player to win both the French Open and Wimbledon in the same season since Bjorn Borg in 1980.
"Right now I am just continuing to try and improve my hard court season."
The 22-year-old, who captured this event in 2005, leads the ATP with 57 wins this year and has captured six titles overall to move to 29 career titles.
In other matches, fourth seed Nikolay Davydenko defeated Tommy Haas 6-3 7-6 (8-6) and fifth-seeded Spaniard David Ferrer moved into the third round with a 6-4 6-4 victory over Robby Ginepri.
James Blake was also a winner as the No.7 seed bounced back from a slow start to post a 1-6 6-1 6-2 triumph over Jonas Bjorkman, but 12th-seeded Tommy Robredo was defeated by Marin Cilic 6-3 6-4.
Andy Murray advanced to the third round with a 6-4 6-4 victory over Sweden's Thomas Johansson.
The Scot is now scheduled to meet Switzerland's Stanislas Wawrinka.
Wawrinka, the world No.10, was a 6-3 6-4 second-round winner over Russia's former world No.1 Marat Safin, who earlier had to complete a first-round match with Sam Querry which had been suspended on Wednesday due to rain.
Richard Gasquet, Igor Andreev, Robin Soderling, Dimitry Tursunov, Jose Acasuso and Nicolas Kiefer all progressed on Thursday.
Defending champion and third seed Novak Djokovic of Serbia moved through to the third round on Wednesday, as did sixth-seeded American Andy Roddick.
Rogers Cup, first and second round results, Toronto
First round result
Marat Safin (Russia) def. Sam Querrey (USA) 6-3 6-3
Second round results
Gilles Simon (France) def. 1-Roger Federer (Switzerland) 2-6 7-5 6-4
2-Rafael Nadal (Spain) def. Jesse Levine (USA) 6-4 6-2
4-Nikolay Davydenko (Russia) def. Tommy Haas (Germany) 6-3 7-6 (8-6)
5-David Ferrer (Spain) def. Robby Ginepri (USA) 6-4 6-4