Top-ranked Roger Federer downed French qualifier Julien Benneteau 6-3, 6-3 to cruise into the third round of the Western & Southern Financial Group Masters.
Other top seeds did not fare so well, with World No. 2 Rafael Nadal, looking nothing like the second-ranked player in the world, and Novak Djokovic, who last week beat the top three players in the world, marking a day of upsets and injuries.
Benneteau held serve in three games in each set as Federer did nothing flashy but seemed to rattle his opponent whenever he chose to go to the net.
"It was a solid match today, and I was happy the way I hit the ball," Federer said. "My slice stayed low. I really hit it well, and my serve was solid, too."
Federer said it was a continuation of the way he played last week in Montreal.
"It was a pity I didn't win it," he said of the Rogers Cup. "I really did play well throughout the week."
Nadal - his right knee wrapped and his left wrist aching - retired in the second set of his match against Juan Monaco of Argentina.
Fourth-seeded Djokovic, who beat Andy Roddick, Nadal and Federer en route to winning the Rogers Cup - the first time anyone beat the world's top three in a tournament since Boris Becker did it in 1994 at Stockholm - fell to Carlos Moya 6-4, 6-1.
"I didn't feel nothing when I touched the racket," Nadal said.
Indeed, he never looked comfortable in the early going, barely managing to hold serve twice. He failed to win a point in his third service game, hitting game point off the edge of his racket into the stands.
Nadal had been bothered by a sore right knee since his Wimbledon final loss to Federer. He said nothing before Wednesday's match indicated any problem with his wrist or arm.
Nadal began to look like his usual self in the eighth game, serving well and dominating. He then broke Monaco to get back on serve, running Monaco from side to side and scoring on two brilliant passing shots, one of which sent Monaco diving to the court in a wild attempt to save a point.
Nadal seemed to be in complete control - until the tie-breaker. After losing that, he took an injury timeout to have his left wrist and forearm massaged and ice applied to in an attempt to relieve the cramping.
When play resumed, Nadal did not win a point in failing to hold serve, and failed to hold again in the fifth game, weakly hitting game point into the net.
Trailing 4-1, he retired, saying it was "stupid to continue playing."
Federer was surprised that Nadal and Djokovic were gone so soon, but said their departure doesn't improve his chances of winning his 50th tournament this week.
"It really doesn't matter who's in the draw, to me," Federer said. "Usually towards the end of the tournament you'll always have the best guys that week in there. If there's a top guy or not, it actually doesn't matter, because the danger is always to be knocked out.
Earlier, Australian Lleyton Hewitt - who needed nearly three hours to beat Stanislas Wawrinka in his first-round match - was on the court only 51 minutes against eighth-seeded Richard Gasquet.
Hewitt won the first set 6-1 and was leading 3-2 in the second when the Frenchman retired with a blister on his right hand.
"Two days ago, I couldn't touch my racket, but yesterday it was better," Gasquet said. "I tried at the warm-up and it was not so bad, but when I played in the match I couldn't."
In Djokovic's case, it was a matter of failing to hold serve just once in the first set, then falling apart completely. He hit just 36 per cent of his first serves in the second set and double-faulted four times.
Even though the top eight seeds got first-round byes this year because of the back-to-back ATP tournaments in Montreal and Cincinnati, Djokovic said it wasn't enough time off.
"I was playing 10 days there and then I had this travelling day. Basically I didn't have a day off," Djokovic said. "I had to play doubles as well on Tuesday. It's not easy."
Altogether, six seeded players were beaten on Wednesday, joining three already gone.
Juan Carlos Ferrero of Spain beat sixth-seeded Fernando Gonzalez of Chile 6-2, 7-6 (7); Nicolas Almagro of Spain beat 11th-seeded Ivan Ljubicic of Croatia 6-4, 6-4; Sam Querry beat 13th-seeded Mikhail Youzhny of Russia 5-7, 6-3, 6-4.
Among the seeded winners, No. 16 David Ferrer beat Radak Stepanek 6-2, 7-5; No. 9 James Blake beat Nicolas Kiefer 6-4, 6-4; No. 11 Tomas Berdych beat Arnaud Clement 7-6 (1), 7-6 (4); and No. 5 Nikolay Davydenko beat Robby Ginepri 6-2, 6-7 (7), 6-3.