who won Olympic gold
at London 2012, is through to the third round of the Rogers Cup in Toronto.
The British number one only arrived in Canada on Tuesday but beat Italian Flavio Cipolla 6-1 6-3.
He required treatment on his knee, which lasted just under 90 minutes.
"I was stiff and sore," said Murray. "I had a lot of matches at the Olympics and this was my first match on a hard court in four months."
Roger Federer and Rafael Nadal apulled out of the event but Murray, who was handed a bye in the first round, will now meet 16th seed Milos Raonic for a place in the quarter-finals.
Organisers presented Murray, who won gold in the singles and silver in the mixed doubles with Laura Robson, with a huge chocolate cake celebrating his Olympic medal.
Jo-Wilfried Tsonga, who won
silver in the men's doubles event at the Olympics,
lost his opening second-round singles match 6-4 7-6 (7-4) to fellow Frenchman Jeremy Chardy.