The World No. 1, despite feeling unwell in sweltering conditions, kept up his title defense with a four-set triumph.

Jannik Sinner battled through illness to reach the quarter-finals of the Australian Open on Monday as his Italian compatriot Lorenzo Sonego ended teenager Learner Tien's fairytale run.

Novak Djokovic was at the centre of another Australian Open row on Monday while Jannik Sinner needed medical attention in fierce heat to battle into the quarter-finals and Iga Swiatek won easily. But American teenage qualifier Learner Tien’s fairytale run is over after he suffered a thigh problem in a four-set defeat to Italy’s Lorenzo Sonego in Melbourne.

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.

Defending champion Jannik Sinner moved into the Australian Open quarterfinals at Melbourne Park on Monday by eliminating the 13th-seeded Holger Rune 6-3, 3-6, 6-3, 6-2.

Jannik Sinner moved into the Australian Open quarterfinals Monday by eliminating Holger Rune in a match paused by medical timeouts and the net detaching from the court.

Jannik Sinner is through to the Australian Open quarterfinals after a drama-filled fourth-round win over Holger Rune. World No. 1 Sinner won in four sets, 6-3. 3-6, 6-3, 6-2, but this did not tell the story of a contest defined by illness.

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.