Volkswacht Bodensee - Sinner defies dizziness to reach De Minaur quarter-final in Melbourne

The world number one and defending champion dropped a set before coming home 6-3, 3-6, 6-3, 6-2 against Danish 13th seed Holger Rune on Rod Laver Arena.

Sinner struggled in the hot Melbourne conditions, his hand visibly shaking and his heart rate taken in the third set before he left court for a medical timeout.

There was then a bizarre 20-minute delay when Sinner demolished the metal brace that secures the net to the floor with a thunderous serve early in set four.

"I was not feeling really well. You know, I think we saw that today I was struggling physically," said Sinner, 23, who is bidding to become the first Italian man to win three Grand Slam crowns.

He refused to say exactly what was wrong with him, only that he was "not there health-wise" and had been "a bit dizzy at times".

"I don't want to go into details. I think it was, you know, then also with the pressure and everything, it was not easy."

He admitted that the time off court in air-conditioning while officials repaired the net helped him refresh.

"I was lucky today that... 20 minutes off court, you know, trying to get back physically, putting some cold water in my head, it was very helpful. It was big, big luck to me today."

Sinner is bidding to defend a Grand Slam title for the first time after beating Daniil Medvedev in the final last year.

His win put him into a clash against home hope De Minaur, who brushed past American Alex Michelsen 6-0, 7-6 (7/5), 6-3 to make his maiden Australian Open quarter-final.

- 'Means the world' -

De Minaur wiped the floor with Michelsen in the opening set, but his serve then faltered and he was forced to a close tiebreak after the American staged a fightback.

But De Minaur broke with a forehand winner in the sixth game of the third set and pulled away for the win.

"It means the world," said De Minaur. "There's nothing I want to do more than play well here in Australia. So glad I finally made the quarter-finals.

"But let's go for bigger and better things."

As temperatures rose above 30 Celsius (86 Fahrenheit), Sinner assumed control against Rune by breaking to love.

Sinner's serve was iron-clad and there was no sniff for the Dane, who went a set down in 33 minutes.

But a Sinner double-fault in the eighth game of set two handed Rune a break, allowing him to hold and level the match as he began to find his rhythm.

It was the second set Sinner had dropped in the tournament, having not done so in 13 previous matches.

Sinner clung on to hold in an epic game three in the third set, which included a remarkable 37-shot rally that he won to save break point.

He gave Rune another break point at 2-2 with a double fault, but again saved, yet he was labouring.

At the changeover, a doctor checked him and he went off for a medical timeout.

Sinner returned and slogged to break for 5-3 before sealing the set.

After the delay while the net was fixed, he produced a top-notch forehand winner to break for 2-1 in the fourth set and there was no way back for a tiring Rune.

H.Kuenzler--VB