Muscular Andy Murray tells Australian media: I'm not too big for my shirt

British No 1 insists the focus on his physique is misplaced despite his intense fitness regime

There is one major question about Andy Murray that appears to be dominating some sections of the media here at the Australian Open.

It is not whether he is happy with his first serve percentage, whether he can become the first player in the Open era to follow up his maiden Grand Slam title with a second, or even whether he thinks Gordon Strachan is the right man to manage Scotland ("We'll have to wait and see how he does," Murray said yesterday). No, the burning question is whether the world No 3 has become too big for his shirt.

Murray has been wearing tight-fitting shirts supplied by Adidas. On a day when the temperature peaked at 40C, perspiration made Murray's shirt cling to him more than ever during his resounding 6-2, 6-2, 6-4 victory yesterday over Portugal's Joao Sousa, which earned a third-round meeting tomorrow with Ricardas Berankis.

Asked after the match whether he would not be more comfortable wearing older-style baggy shirts, Murray said: "The only thing I don't like on shirts is if they come down too low and sometimes your elbows can get caught in the shirt. The less material there is on the shirt I think probably the better. There's less to get in the way. But so long as they're tailored somewhat, I think there's no real problem."

Murray shows little interest in on-court fashion ("I let Adidas decide those things – I just play") and insisted that any impression that he was broader across the chest as a result of his training was misleading.

"Most of the weight that I put on is in my legs, but the T-shirt I'm wearing is tighter," he said. "It's not that I'm any bigger in my upper body. It's just because of the tightness of the T-shirt. Maybe it appears that way."

However, there is no doubt that the modern game has become more physically demanding and that players are stronger. Novak Djokovic beat Murray in a semi-final here last year that lasted nearly five hours and overcame Rafael Nadal in a near six-hour final two days later.

Murray believes that Nadal played a big part in changing the way that players look. "Rafa was the first one to have that physique that looked like a true world-class athlete across any sport," Murray said. "Tennis players are always in good shape, but I think he looked like he could do any sport.

"The game has changed for sure physically. It's much more demanding and I've adapted my preparation and training. Reducing the amount of tournaments I play and spending more time getting myself ready for events is the best way to prepare. Still not everybody does that, but I believe that's the best way to go about it, spending more time in the gym in the off-season."

The Australian newspaper yesterday revisited comments by Christophe Rochus, a retired Belgian player, who has made allegations of drug abuse in tennis. "The guys can't play five or six hours and then come back the next day and run around like a rabbit," Rochus was quoted as saying. Murray rejected his claims.

"I would say that is far from the truth," he said. "Anyone can see the amount of hours of training and practice that go into what we do and there are other sports that are far more challenging than tennis endurance-wise. When guys play five or six hours in the Slams, like we often do, we have a day's rest.

"I was told that on his day off after our match here last year Novak didn't practise, didn't hit a ball, didn't get out of bed until three o'clock. Providing you put the work in it doesn't mean it hurts any less when you have to play a couple of days later after a five-hour match but I would not say it's impossible."

On a scorching afternoon yesterday Murray never looked troubled by the heat. He thoroughly outclassed Sousa, winning in an hour and 41 minutes. The Scot broke serve five times and did not have to defend a single break point.

Murray's next opponent is one of those players attempting to prove that bigger does not necessarily mean better. Berankis is only 5ft 9in tall, but the 22-year-old Lithuanian packs a decent punch. Having played three matches in qualifying, he has won five matches here for the loss of just one set. He claimed his biggest scalp yesterday, beating Florian Mayer, the world No 28, 6-2, 6-3, 6-1.

A former world junior No 1 who was invited to train with Roger Federer in Dubai three years ago, Berankis was Lithuania's key player in their historic Davis Cup victory over Britain in 2010. He is currently world No 110 after two seasons which were disrupted by a groin injury.

Murray, who has practised several times with Berankis, said: "He hits the ball pretty big from the back of the court. He plays aggressive. He's a very flat hitter of the ball. He's obviously playing well to beat a guy like Mayer that comfortably."

While Murray can be expected to wear the same shirt tomorrow, he will not be changing to the shorter style shorts which some players have been wearing here.

"I actually wore a pair at Wimbledon when I was with Fred Perry that were short, though not quite like what Ivan [Lendl] and those guys used to wear," he said. "I can't see a return to them, to be honest. They were a bit too short. They didn't leave too much to the imagination."