Alex de Minaur to face Jannik Sinner as the 'underdog' in Australian Open quarterfinal

With an 0-9 win-loss record against Jannik Sinner, it's little wonder Alex de Minaur has assumed "underdog" status ahead of their Australian Open quarterfinal on Wednesday.

"The great thing about tennis is that once you step out on the court you both start at 0-0, right?" de Minaur told reporters after his fourth-round win over Alex Michelsen.

"It's a whole new day, a whole new match and anything can happen.

"Sport is unpredictable. That's exactly the mindset I'm going to have going into that match. I'm looking forward to it."

De Minaur — making his first appearance in the quarterfinals of his home major — faces an imposing task if he's to beat the world number one and defending champion for the first time.

But speak to Michelsen, who de Minaur defeated 6-0, 7-6 (7/5), 6-3 on Monday night, and it's clear all is not lost for the eighth-seeded Australian.

The American gave a hint on how de Minaur can beat Sinner, although he's aware of how challenging the assignment will be.

"I think against Sinner he's going to have to not miss a single ball if he wants a chance, because Sinner is just unbelievable," Michelsen said on Monday night.

Alex Michelsen (right) feels de Minaur needs to play to his strengths against Sinner. (Getty Images: Graham Denholm)

De Minaur's court coverage and foot speed are crucial if he's to compete with Sinner, according to Michelsen.

"I think Alex makes a lot more balls than all three of the guys that I played [before the fourth round]," he said.

"He doesn't miss a ball, doesn't give anything for free."

Michelsen also encouraged de Minaur to play to one of his other strengths: his backhand.

De Minaur is finally where he wants to be Photo shows Alex de Minaur of Australia celebrates winning the second set. After telling fans on the weekend his "legs are back", Alex de Minaur proved it on his way to the Australian Open quarterfinals.

"His backhand is absolute money. He doesn't miss it," Michelsen said.

"He was hitting his backhand line super well today. I wasn't expecting that, honestly."

Sinner revealed he was feeling ill and experiencing dizziness against 13th seed Holger Rune in the round of 16, having needed a medical timeout during the four-set win.

But Michelsen was unsure if Sinner's physical condition would play into de Minaur's hands, considering the Italian's mental toughness.

"I saw he (Sinner) was struggling today. I don't know what he had," Michelsen said.

"I don't know what it was, but he got through it. Not surprising."

De Minaur's serve gone on 'vacay'

De Minaur's serve needs to be on song if he is to have a chance of reaching the semifinals. (Getty Images: Shi Tang)

Michelsen did note de Minaur's serve is on the "weaker" side, although he acknowledged it had improved since they first played each other last February in Los Cabos.

Sinner struggles in heat at Australian Open Photo shows Jannik Sinner with towels over his head at the Australian Open. With the temperature rising above 30 degrees Celsius, Jannik Sinner battles his way through to the last eight with a four-set win over 13th seed Holger Rune.

De Minaur knows he needs to lift his first serve percentage, which has dipped below 50 per cent in the past two rounds.

"I think last couple of matches those serves just decided to go away on a little vacay (vacation), kind of deserted me for a little while," he said.

But he added: "I'm sure my serve will come back."

It will be an upset if de Minaur takes down Sinner, but the 25-year-old is comfortable not being considered the favourite.

"[They're] The matches I want to be playing," de Minaur said.

"Ultimately, if there is anything, it's going to be my first match this whole tournament where I'm the underdog and don't have all the pressure and expectation of having to win.

"So it's quite exciting and I'm looking forward to that."

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