WATCH: There's a screw loose at Australian Open, as Sinner's win over Rune interrupted by net problem

MELBOURNE, Australia (AP) — The screw holding the net in place at the Australian Open’s main stadium got jarred loose during defending champion Jannik Sinner’s fourth-round victory against Holger Rune on Monday, delaying play for about 20 minutes early in the fourth set.

After finishing his 6-3, 3-6, 6-3, 6-2 win to return to the quarterfinals, Sinner acknowledged the break “was very helpful” on a day that he struggled physically and sought medical attention with the temperature above 90 degrees Fahrenheit (32 Celsius).

“Obviously, nobody was expecting this kind of thing. Usually when the net breaks, it’s not the bottom,” Sinner said. “I was lucky today.”

The No. 1-ranked Sinner, who is the defending champion at Melbourne Park, hit one of his booming serves into the net, shaking it. That managed to inadvertently undo the metal piece that hooks into the bottom of the black webbing that separates players on a tennis court, then is rotated to screw into the blue-painted surface.

That left the net loose, so play could not continue. At least a half-dozen people went over to take a look at things and attempt to re-connect the equipment. Eventually, a worker with a red tool box was able to fix it, earning a cheer from thousands of spectators at Rod Laver Arena.

“This is probably something that will happen one out of 500 matches. It’s very rare,” Rune said. “There’s nothing to do about it. The net broke. Boom. That’s it. We just had to wait.”

In the meantime, chair umpire Nico Helwerth sent both Sinner and Rune off to the locker room so they did not need to sit on the sideline in the afternoon heat.

“Ladies and gentlemen, as you can see, we are trying to fix the net as quick as possible,” Helwerth announced to the crowd. “It’s probably going to take a few minutes. Thank you for your patience.”

Each player already had taken a medical timeout during the match. Sinner was leading 6-3, 3-6, 6-3, 0-1 when action was halted.

As Sinner and the 13th-seeded Rune, a 21-year-old from Denmark, walked back out on the court to return to the contest, fans applauded.

The players were then allowed to warm up for three minutes before Sinner got things started again with a serve.