Top seed Daniil Medvedev battled back from two sets down and saved a match point against Canada's Felix Auger-Aliassime to reach the Australian Open semi-finals with a 6-7(4) 3-6 7-6(2) 7-5 6-4 victory.

The 25-year-old Russian had his back firmly up against the wall for much of an absorbing contest as Auger-Aliassime produced some stunning tennis on Rod Laver Arena.

But he simply refused to lie down as he overturned a two-set deficit for only the second time in his career to set up a Friday semi-final against Greek Stefanos Tsitsipas who he beat at the same stage a year ago.

It was the kind of resilience absent nine-time champion Novak Djokovic has trademarked and Medvedev, the reigning US Open champion, said he had taken inspiration from the Serbian to get out of trouble.

"At two sets down I was not playing my best and Felix was playing unbelievable, serving unbelievable, he was all over me to be honest. I didn't know what to do so I told myself 'what would Novak do?" Medvedev said on court, prompting some boos.

"What came to mind, was that I thought if Felix wants to win it he will have to fight for the last point.

"I managed to raise my level and when they closed the roof I felt the momentum and started serving better."

Stefanos Tsitsipas went through in straight sets

Tsitsipas will be hoping it is third time lucky in an Australian Open semi-final after his scintillating 6-3 6-4 6-2 victory against Jannik Sinner.

The fourth seed, a semi-finalist in Melbourne in 2019 and 2021, was stretched to five sets by Taylor Fritz on Monday but showed no signs of fatigue in a match that started in blazing sunshine but finished under the roof after a storm hit.

With Melbourne's big Greek population, 23-year-old Tsitsipas has always drawn strong support at the Australian Open and it was the same again in the clash against Sinner.

"I think my humility helped a lot today. I knew I was going on the court facing a very good player. I tried to focus on my best shots and it paid off more than I thought," he said in his on-court interview.

"Once again, stepping on to that court, having the crowd support, it is truly unbelievable."

A finalist at Roland Garros last year, Tsitsipas was troubled by elbow problems at the end of last season and was concerned he might not be able to play in Australia.

"I am pretty sure my doctor is watching right now. He has been sending me texts after every single game," he said.

"He said 'I don't expect to see you playing in Australia'. But I proved him wrong. I am happy I have found the right man to bring me back even stronger."