Jannik Sinner battled through illness and reached the quarter-finals of the Australian Open but the physical demands of Grand Slam tennis proved too much for French veteran Gael Monfils and American teenager Learner Tien.

Iga Swiatek was in excellent shape as she continued her bid for a maiden title at Melbourne Park and sixth major by downing lucky loser Eva Lys 6-0 6-1, but Elena Rybakina could not shake off a back problem and fell 6-3 1-6 6-3 to Madison Keys.

Monfils, 38, was forced to retire with his own back issue while trailing American young gun Ben Shelton 7-6(3) 6-7(3) 7-6(2) 1-0, ending an inspired run at the year’s first Grand Slam after his Auckland triumph.

Gael Monfils of France during his game against Pedro Martinez of Spain in the Round 1, R32 Men’s Singles Match of the 2025 Men’s ASB Classic.
Photo: Andrew Cornaga / www.photosport.nz

The stifling heat did not help defending champion Sinner when he started struggling physically in the second set of his fourth-round clash with Dane Holger Rune on a steamy afternoon at Rod Laver Arena.

The top seed did not want to go into detail on what was ailing him but admitted to having dizzy spells before a lengthy medical timeout in the third set that proved a turning point in his 6-3 3-6 6-3 6-2 victory.

“I wasn’t feeling really well,” said 23-year-old Sinner, who equalled the Italian record set by Nicky Pietrangeli by reaching his 10th Grand Slam quarter-final. “I think we saw that today, I was struggling physically.”

Alex de Minaur.
Photo: RICHARD WAINWRIGHT/Photosport

Sinner will next face home hope Alex de Minaur after he beat rising American Alex Michelsen 6-0 7-6(5) 6-3 to reach the Australian Open quarter-finals for the first time.

“There is nothing I want more than to play well here in Australia. Glad I finally made it to the quarter-finals here but yeah let’s go for bigger and better things, come on!” eighth seed De Minaur said after the Rod Laver Arena night match.

Unseeded Lorenzo Sonego made it two Italians in the quarter-finals when he defeated hobbling 19-year-old American qualifier Tien 6-3 6-2 3-6 6-1, having also taken out Brazilian young gun Joao Fonseca in the second round.

“I’m so sad that he had a problem,” said the 29-year-old Sonego, who has never previously gone so deep at a Grand Slam and will face Shelton next. “It’s not the right way to win.”

Tien, who was bidding to become the youngest man to reach the quarters since Goran Ivanisevic did it as a 17-year-old in 1989, stretched his strapped right thigh after a double fault and never looked comfortable physically.

American tennis player Learner Tien
Photo: PHOTOSPORT

Ivanisevic was part of Rybakina’s team at Melbourne Park with her coach Stefano Vukov banned for the tournament by the WTA for a potential code of conduct breach.

The former Wimbledon champion said it was hardly an ideal situation and she was still feeling a back issue but was making no excuses after her loss to Keys in a roller-coaster match on Margaret Court Arena.

“I had some opportunities, but it is what it is,” the disappointed sixth seed said. “I need to work better.”

‘Spirit of Ukraine’

Keys was delighted to be back in the last eight at Melbourne a decade after the first of her two runs to the semi-finals.

“It’s hard to believe that it was 10 years ago,” she said. “But really proud of myself … to be out here and still playing some good tennis all these years later, I’m happy.”

Keys will next play a familiar foe in Elina Svitolina, who brought a “little light” to war-torn Ukraine by beating Russian Veronika Kudermetova 6-4 6-1 in the opening singles match.

Elina Svitolina.
Photo: AFP

The 30-year-old Ukrainian was 4-1 down in the first set but rallied for a comfortable victory before writing the message “the Spirit of Ukraine” on the camera before she left the court.

“I was extremely motivated to win today, so that people in Ukraine wake up to good news,” said Svitolina, who moved to 7-0 against Russian players since the 2022 invasion of her homeland.

“For me, to find a way to win matches, to find a way to bring a little light, a little win for Ukrainian people is something that I feel I am responsible of.”

Svitolina was back on Margaret Court Arena later to cheer on her husband Monfils, but there was no double delight.

That was reserved for Swiatek, who after her win got news that the World Anti-Doping Agency (WADA) would not appeal to the Court of Arbitration for Sport in her doping case after she tested positive for trimetazidine last year.

The Pole had accepted a one-month ban after explaining that her positive test was the result of contamination of her sleep medication melatonin.

Sinner is still facing the prospect of a ban after testing positive for the anabolic agent clostebol last year. The Italian was also cleared of wrongdoing, but WADA appealed to sport’s highest court, with a hearing starting on April 16.

A relieved Swiatek will next meet American Emma Navarro, who beat Russian Daria Kasatkina 6-4 5-7 7-5.

– Reuters