Olympic gold medallist Andy Murray and top seed Novak Djokovic both avoided post-Games letdowns with quick opening wins at the Toronto masters.
Murray, fresh from his home success at Wimbledon, on Wednesday toughed out a painful 6-1, 6-3 defeat of Flavio Cipolla. Djokovic avoided most of the pressure in his 71-minute defeat of Bernard Tomic 6-2, 6-3 sealing three match points with a sixth ace and going through on the first match point.
"For the first match it was a decent performance. Obviously at the start we played very long opening four games, and I was struggling to find the rhythm as most of the players who came in late from London did," said Djokovic.
Murray, who only arrived in Canada on Tuesday from London, took the hardcourt with minimal preparation but pulled off the win in just under 90 minutes thanks to some help from the ATP trainers.
The number four was treated on his left knee after breaking Cipolla for 3-2 in the second set. Murray was then constantly flexing the knee on his way to victory.
"I feel a little bit sore in the joints, I feel tired mentally," said Murray, "I haven't really slept much the last few days, so that's probably catching up with me a little bit.
"I hit the ball pretty well. After playing for eight weeks on grass, it's very different here. The ball is very quick compared with Wimbledon. It also bounces much higher. The court is much slower as well."
The Scot won the Canadian titles in 2009-10, but lost his opening match a year ago.
Organisers presented Murray with a huge chocolate cake celebrating his Olympic medal, with a replica of the honour and its ribbon made of icing.
Given a knife during an on-court ceremony, the gluten-free player gratefully cut off the huge medal corner and took a fork full.
"I haven't had much time since winning the gold," he said. "The last few days have been unbelievable - a bit surreal. I've been very busy but it's worth it."
While Murray survived, doubles silver medallist Jo-Wilfried Tsonga went down in his opening second-round singles, losing as French underdog Jeremy Chardy sprang a post-Olympic surprise on his third-seeded countryman 6-4, 7-6 (7/4).
Like Murray, Tsonga - who has never lost before the semi-finals in Canada - said he was tired.
"I'm disappointed because I lost it, but this is the rule. I have to play every week, I have to be here.
"I will not complain. I will just say, 'Okay, next week I have another tournament,' I will have some rest, and that's it."
Chardy, ranked 47th, was playing for the second day in a row while Tsonga was on court three days after playing in the men's Olympics doubles final with Michael Llodra against the American Bryan brothers.
For Olympic participants, this week marks a return to North American hardcourts after nearly five months on clay and grass.
London bronze medallist Juan Martin del Potro, the Argentine sixth seed, went out to Czech Radek Stepanek 6-4, 7-6 (7/5).
"I came here Monday night, many players pulled out from here," said the fatigued South American who looks likely to head straight home for some rest. "It's not easy to play after a big effort in the Olympics, but I tried anyway.
"Now I need time to recover my body if I want to stay healthy."
Other seeds managed wins, with Olympic first-round loser Tomas Berdych rallying past Julien Benneteau of France, 6-7 (10/12), 6-4, 6-4.
Number five Serb Janko Tipsarevic defeated Russian Mikhail Youzhny 7-6 (7/2), 6-4 while Croatian Marin Cilic, the tenth seed, beat Marcos Baghdatis 7-5, 6-3.