Murray, fresh from his home success at Wimbledon, 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 hard-court 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."

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).

London bronze medallist Juan Martin del Potro, the Argentine sixth seed, went out to Czech Radek Stepanek 6-4, 7-6 (7-5). AFP