Toronto, Canada, 9 August 2012 | AFP

Defending champion Novak Djokovic has eliminated Australian Bernard Tomic from the Toronto Masters.

The world No.2 beat Tomic 6-2 6-3 in their second-round match to join Olympic gold medallist Andy Murray in the last 16.

Djokovic out-served the Aussie throughout the one hour, 11 minute contest, winning 86 per cent of points on his first serve and saving all six of the break points he faced.

Tomic, meanwhile, struggled on serve, winning just eight of 23 second serve points.

Djokovic next goes on to play American Sam Querrey, while Tomic will next head to Cincinnati, another prestigious Masters 1000 event on the ATP World Tour.

Murray ground out a painful opening win on Wednesday as the second seed marshalled his resources for a 6-1 6-3 defeat of Flavio Cipolla.

The Scot who only arrived in Canada the day before following his Olympics media duties on Tuesday, but pulled off the win in just under 90 minutes thanks to some help from the ATP trainers.

The world No.4 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 and 2010, 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(4).

Like Murray, Tsonga – who has never lost before the semifinals 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.”

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(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(12) 6-4 6-4.

Number five Serb Janko Tipsarevic defeated Russian Mikhail Youzhny 7-6(2) 6-4 while Croatian Marin Cilic, the tenth seed, beat Marcos Baghdatis 7-5 6-3.