Jannik Sinner, the world No 1 and defending champion, looked to be heading out of the Australian Open until he was rescued by a controversial medical time-out.

On the hottest day of the tournament so far, Sinner was dizzy and pale-faced as he split the first two sets with the dangerous Dane Holger Rune. Sinner’s hands could be seen shaking violently as he held a towel over his face at a changeover early in the third set.

The doctor attended Sinner at the next changeover, and he went off court for a six-minute consultation while Rune – in his own words – was left “sitting in the heat, cooking out there”.

In the circumstances, it seemed slightly tactless of Sinner – who has already been accused by many players and fans of benefiting from preferential treatment over his positive tests for Clostebol in March – to spend his on-court interview thanking the Australian Open for looking after him.

“The time off the court, me and the doctor talked a little bit,” Sinner told Jim Courier. “It helped me today and also shows this tournament has great organisation. They really take care of the players.”

Once the players had reached the interview room, Rune acknowledged that he had been naive not to leave the court as well during that first lengthy stoppage. But as he explained: “It took longer than I expected. It was around 10 minutes, maybe even more. So that was a bit brutal in the middle of the set. I had good momentum in this moment. So, yeah, it was not the worst timing from his side.”

Sinner’s own view of the time-out was that “I at least felt slightly better when I went back on court. I felt like the face looked a little bit better, the colour was a little bit back. He gave me some small medication.”

Sinner went on to win that set, and was then able to take a second long break from the court when he broke the net at the start of the fourth set. This was a true rarity, “something that will happen one out of 500 matches”, according to Rune. It happened when Sinner banged a 124mph first serve into the net tape, and the screw that attaches the centre of the net to the court surface popped right out of the ground.

This delay was even longer: fully 20 minutes, in fact, to find a bigger screw. While both players had a chance to rest and recuperate this time, it did not seem to help Rune much. He had spent 10 hours on the court reaching this fourth-round match, playing two five-setters and one four-setter along the way, and his knee began to give way.

“I had knee issue the last year,” said Rune afterwards, “so stopping in the middle of everything and having to reactivate was a bit tough. It was a three-hour-and-15-minute match, but I think we had 45 minutes break in the whole match, so it was very, very long.”

‘I knew I would struggle today’

Having finally seen off Rune by a 6-3, 3-6, 6-3, 6-2 margin, and thus set up a quarter-final against home favourite Alex de Minaur, Sinner told Courier that he had been suffering from unspecified health issues even before he went out to play in the 32C heat of the Australian sun.

“Today was a very strange morning,” he said. “I didn’t even warm up today, trying to go on court as fit as I could. I knew in my mind. I would struggle today.”

Later, he was quizzed further about his health by reporters. “I think we saw that I was not feeling well,” Sinner replied. “I was a bit dizzy at times. I don’t want to go in details. Also with the pressure and everything, it was not easy.

“It helped me,” Sinner added, when asked about the broken net. “I was lucky today that, [I got] 20 minutes off court. Trying to get back physically, putting some cold water in my head, it was very helpful. It was big, big luck to me today.”