MELBOURNE, Australia >> First came the medical timeouts, one each for Jannik Sinner and Holger Rune with the temperature above 90 degrees Fahrenheit (32 Celsius) at the Australian Open.

Then came the bizarre sight of a 20-minute delay because the net at Rod Laver Arena detached from the court after being hit by a big Sinner serve.

In the end, the breaks in action were “lucky,” Sinner said, because they gave him a chance to catch his breath, put his struggles aside and emerge with the victory — as he keeps doing, no matter the site or the circumstances. The defending champion moved into the quarterfinals at Melbourne Park on Monday by eliminating the 13th-seeded Rune 6-3, 3-6, 6-3, 6-2.

“I don’t want to talk so much (about) how I felt today. I was not feeling really well. I think we saw that today. I was struggling physically,” Sinner said, declining to say exactly what was wrong. “Playing against a tough opponent, but also playing against myself a little bit.”

The No. 1-ranked Sinner occasionally tried to cool off by pressing a cold towel to his face or pouring water down the back of his neck. He was far better down the stretch, both after a 10-minute-plus delay in the third set when he went to the locker room for medical attention and after a 20-minute holdup in the fourth when the screw connecting the net to the blue playing surface came undone.