Defending champion Jannik Sinner made it through to his ninth consecutive Grand Slam quarter-final with a straight-sets victory over fellow Italian Luciano Darderi to stay on course for a third consecutive title in Melbourne.

Sinner, who battled back from the brink of a cramp-induced breakdown to keep his title defence alive against Eliot Spizzirri in the last round, stayed on course for a three-peat with a much more straightforward win over 22nd seed Darderi 6-1 6-3 7-6 (7-2).

The four-time Grand Slam champion was dominant in short rallies but suffered a wobble in the third set before completing victory in a tie-break.

Temperatures are on the rise again in Melbourne, with the peak of the heat expected on Tuesday, but Margaret Court Arena was in shade when Sinner and Darderi took to the court.

"It was very, very difficult," admitted Sinner, who has never lost to a fellow Italian at tour level, extending his winning record to 18-0.

"We were good friends off court. It's a small difficulty to also put away. I felt like in the third set I had a couple of break chances but couldn't use them, then I got very very tight. I'm very happy I closed it in three sets."

The 22nd seed possesses a powerful forehand and saved two match points at 5-4 before taking an early lead in the tie-break but Sinner responded emphatically, winning seven points in a row.

Sinner, who struck a Grand Slam career-best 19 aces in the match, said he has put "a lot of work" into his serve.

"We changed the motion a little bit. I feel a bit more confident but I feel like there's still room to improve.

"Now it's a bit more stable but it's not only that area where we have to improve. I will try to go a bit more to the net and being slightly more unpredictable, which I felt like worked really well."

Lorenzo Musetti ‌produced an inspired display to ease past American Taylor Fritz ​6-2 7-5 6-4 to reach the Australian Open quarter-finals for the first time, setting up ​a meeting with 10-time ​champion Novak Djokovic.

The Italian came through a five-set battle ‍with Tomas Machac in the last round but it did not appear to have ‌taken much out of him as he broke ‌Fritz's big serve twice in the opening set.

Musetti played with ​authority and artistry towards the end of the second set, which he secured by ‍winning three straight games, before breaking early in the third set to heap the pressure on the American.

Ninth seed Fritz, who ‌was moved all over the ⁠court by his 23-year-old opponent, dug ‌deep to stay in touch ‍but Musetti served out the victory in style for a tantalising meeting with 24-times major champion Djokovic.

The Serb had already advanced to the last eight ​after his fourth-round opponent Jakub Mensik withdrew due to an abdominal injury on Sunday.

"Novak, we've played many, many ‍times and every time it's a lesson, first of all," said Musetti, who has won only one of his 10 meetings with the 38-year-old.

"It's such an honour to share the court with him, and every time I leave the court with something I really think is helping me to try to win against him.

"He didn't ​have to play today, so I'm pretty sure he won't be tired. Hopefully the rhythm I have right now with the great match today will bring me luck for the next one.

"I feel ready to try ‍to push him to the maximum."

Musetti's run here, meanwhile, has come despite the early departures from Australia by two of his team - including coach Simone Tartarini - for personal reasons.

"Real life knocks on the door sometimes," said the 23-year-old. "It's something surprising. It makes you understand life better. I feel more mature and I'm playing better for them."

Fritz cut a downbeat figure regarding the state of his troublesome knee after his previous victory over Stan Wawrinka, while he also needed treatment for an abdominal issue.

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