Jannik Sinner battled through illness to reach the quarter-finals of the Australian Open on Monday as his Italian compatriot Lorenzo Sonego ended teenager Learner Tien's fairytale run.
Madison Keys later turned back the clock to stun Elena Rybakina and Elina Svitolina brought a "little light" to war-torn Ukraine by beating Russian Veronika Kudermetova 6-4 6-1 on another hot day in Melbourne.
The stifling heat did not help defending champion Sinner when he started struggling physically in the second set of his fourth-round match against Dane Holger Rune on 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 was not 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. Came here as late as possible. I knew that it was going to be very, very difficult today."
Unseeded Sonego made it two Italians in the quarter-finals when he stopped 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.
"It's not the right way to win, but I'm so happy to reach the quarter-finals."
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.
Ivanisevic was part of Rybakina's team in Melbourne 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 6-3 1-6 6-3 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 Park 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 today ... to be out here and still playing some good tennis all these years later, I'm really happy."
Keys will next play a familiar foe in Svitolina, who beat Kudermetova in the first singles match of the day.
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 in the day to cheer on her husband Gael Monfils but there was no double delight as the 38-year-old Frenchman retired while trailing American Ben Shelton 7-6(3) 6-7(3) 7-6(2) 1-0.
Shelton will play Sonego in the last eight, while Sinner will next face either local hopeful Alex de Minaur or American young gun Alex Michelsen, who meet in the final match of the day on Rod Laver Arena.
