Jannik Sinner struggled with a cramping spell in extreme heat on Saturday at the Australian Open, with the two-time defending champion benefitting from the tournament heat rule to survive a feisty first-time opponent.

The second seed held off qualifier Elliot Spizzirri, making his main draw debut here, taking more than three and a half hours to wrap up a 4-6, 6-3, 6-4, 6-4 fightback into the fourth round.

Sinner lost his first set since late October (Vienna final) but held on for an 18th consecutive win to advance as temperatures rose toward 40 Celsius.

Under the heat policy, the roof of the Rod Laver showcourt was closed early in the third set, a development – along with the ensuing 10-minute pause – which may have saved the seed’s chances.

“If he had continued playing in the way that he was, my tournament might have been over,” Sinner said.

The 85th-ranked Spizzirri won the opening set , twice coming from a set down to stun the Italian who has won the last two editions here.

Sinner was treated on the sidelines for cramping a few games later and completed his face-saving comeback as his opponent netted in the fourth set on a second match point.

“I struggled physically today but I got lucky with the heat rule,” the winner said. “The cramping started with the legs and moved to the arm; it was a bit all over.

“But I took my time and as it passed I felt better. I’m happy with this performance. After such a tough match I hope it gives positive feelings to start the next round with a good mentality.”

Sinner added: “Tennis is a very mental game, I tried to stay as calm as possible.

I’m here to fight and play in the best possible way.”

The winner said he and his team will be working on strengthening his endurance in hot conditions which can occur without much warning in the Australian summer.

“But for now, I’m glad I have at least one more match to play here. It’s time for recovery and to get ready for the next round.

Spizzirri was proud of his spirit and fitness after the biggest match of his career.

“I’m most happy with the fact that my body held up for two grueling matches and then this one as well, so three.

“Today was tough, there were definitely some additional nerves going out against Jannik – first time for me on one of the bigger stages in the sport.

“I was happy with the way that I was executing the game plan and committing
to what I wanted to do, but at the same time I knew that he was going to adjust.”

Sinner’s fellow Italian Lorenzo Musetti followed the winning formbook as he completed his personal quarter of fourth–round places in each of the Grand Slams.

The fifth seed did it with a 5-7, 6-4, 6-2, 5-7, 6-2 marathon victory over Tomas Machac which took a shade under four and a half hours in the draining heatwave conditions.

A third Italian, Luciano Darderi, came through for a defeat of Karen Khachanov 7-6 (5), 3-6, 6-3, 6-4, placing three Italians in the fourth round here for the first time..  

Ten-time champion Novak Djokovic benefitted from the relative cool of the evening, dominating Dutchman Botic Van De Zandschulp 6-3, 6-4, 7-6 (4) to reach the fourth round of a major for the 70th time.

The win moves the 38-year-old Serb into position as the only man to have ever won 400 matches at the majors.

Djokovic at one point hit a ball in anger, barely missing a ballkid and thereby avoiding an automatic DQ.

The 24-time Grand Slam champion, still in the mix as he aims to make more history with a record 25, was happy to escape with the win over Van De Zandschulp in two and three-quarter hours.

“I’m still trying to give the young guys a push for their money – I’m still around.

“When you enter the court there is always a chance. This is the court that has given me the most in my career (10 titles).”

Djokovic controlled the first zet and a half but had a scare when he took a fall, managing to save his ankle as he tumbled.

“After that the tables turned, I relaxed a little too much and had trouble closing out the set.

“From then on it sas anyone’s game. I was lucky to get out of trouble in the third set, I’m just glad to win in straight sets.”

Eighth seed Ben Shelton showed some of his best tennis,firing 48 winners and just 28 unforced errors to advance 6-4, 6-4, 7-6 (5) over Monegasque Valentin Vacherot.

Taylor Fritz ended the Melbourne career of 40-year-old three-time Grand Slam champion Stan Wawrinka, with the Swiss due to retire at the end of 2026 taking a 7-6 (5), 2-6, 6-4, 6-4.

Fritz rained down more than 30 aces and paid tribute to the legend that is Wawrinka as the Californian moved into a match with Lorenzo Musetti.