Tuesday, 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 was stiff and sore," Murray said. "I had a lot of matches at the Olympics and this was my first match on hardcourt in four months."
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 dead-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 final with Michael Llodra against the American Bryan brothers.
French 14th seed Richard Gasquet opened with a victory over Mikhail Kukushkin of Kazakhstan 6-3, 7-5.
Tsonga was the day's most notable early victim of Olympic fatigue as the ATP schedule hits a run of two straight weeks of 1000-point events before the start of the US Open on August 27.
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."
Del Potro, a former US Open winner, wants to regain his full powers on court before the start of the final major of what has been a busy season. "This was my first match on hard courts since Miami (March).
"But now I will have time to relax, to train, and I will be 100 per cent for the next tournaments and 100 per cent for my favourite tournament in New York."
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.