Jannik Sinner is not making it easy for himself this year. Matches he would have expected to sprint through here have become mini-marathons and there is the small matter of another ­heatwave arriving in London this weekend, which, as we saw in Paris, is his kryptonite.

More worrying, as Sinner ­admitted after reaching the last 32 with a 7-6 (4), 7-6 (2), 6-4 victory over the world No 48, Nuno Borges, his game is still falling short. The forensic analysis started when the Italian was asked whether his forehand was as good as it could be.

“No, it’s not,” came the reply. When the follow-up came about which other areas in his game needed improving, it turned into quite the list. “I’m trying to go a little bit more to the net,” he said. “Trying to be a bit more aggressive. Also, the movement itself can improve on grass.

“The return of serve, especially ­second serves, trying to be a little bit more aggressive, then we see how it goes. All shots I can do slightly ­better. But second match on grass, I was not looking for perfection. I tried to improve. Felt like at times I did. Now we’ll see how it goes.”

As Sinner said, he was far ­better against Borges than he was when toiling to a five-set victory against Miomir Kecmanovic on Monday. Yet the amount of time he is spending on court will surely concern him.

Last year, Sinner breezed through the opening week here. In his first three matches he lost 17 games and was on court for five hours and 15 minutes. This year? In two matches, ­Sinner has lost 39 games and been on court for six hours and two minutes.

His stamina has long been questioned and with temperatures in London forecast to rise to 31C (88F), he hardly wants to be expending too much of it too early.

Asked whether he preferred a tougher start to get his grass-court legs under him after not playing a warm-up tournament, Sinner said he was uncertain. “For sure, for the first match on grass, having a tough opener, then getting through, was important.

“Today, I managed the first couple of sets very well in tricky moments. I know I can, or hopefully I can, play a little bit better at times. Hopefully comes match by match, then we see.”

It was hardly a convincing answer. Then again, Sinner remains the overwhelming favourite to win the tournament and thus retain his title. Because, in the absence of Carlos Alcaraz, ­everyone else will be a long shot against him.

Future opponents, though, will surely note that Borges had his chances. After losing a tight set, he had set point at 5-4 in the second only to squander a makeable shot into the net. A fortunate Sinner net cord was followed by another Borges error and before long the game and second set had gone.

The third set was not entirely smooth either – Sinner was broken again before recovering – but a shock never looked on the cards.

“The second set was important,” he said. “The dynamic can change in the third set if you go up two sets to love. That’s what happened. I broke him very early. Was a lack of concentration again in the third set. But I tried to bounce back straight away, which I’ve done.”

Sinner should have little ­trouble with the unseeded Jenson Brooksby in the third round on Friday. Brooksby has a nice game, but a weak serve and does not appear to possess the firepower on the ground to ­trouble the world’s best player.

The American certainly said all the right things after his straight-sets victory over the No 32 seed, Igancio Buse. “It would probably be one of the couple toughest challenges right now in tennis, just for how ­consistently he’s been winning slams or big events. But I’m always someone who loves that challenge. I never doubt my ability to be able to beat someone.”

Sinner will backing himself to find the old magic once again. “I need to get back to the rhythm, but matches like these help me a lot,” he said.