Rafael Nadal stayed on course for a record 21st Grand Slam title at a fan-free Australian Open on Saturday as Ashleigh Barty gave locked-down Melbourne something to cheer.
As Victoria state went into a snap, five-day lockdown to curb a coronavirus outbreak, Daniil Medvedev, Stefanos Tsitsipas and Andrey Rublev all reached the last 16 at an eerily empty Melbourne Park.
But world number one Novak Djokovic, the defending champion and holder of a record eight Australian Open titles, faced a race to be fit for his third-round clash on Sunday.
The Serb, who said he tore an abdominal muscle during Friday's five-set win over Taylor Fritz, skipped training and sought medical advice and treatment on Saturday. He is scheduled to play Canada's Raonic late on Sunday.
The loss of Djokovic, 33, would be another blow for the tournament, reducing the men's 'Big Three' to just one -- Nadal -- with Roger Federer already sidelined by injury.
Nadal, who has his own injury concerns with a stiff lower back, faced down his toughest test so far with a 7-5, 6-2, 7-5 win over British fellow leftie Cameron Norrie.
"The feeling is completely different -- nobody wants this," said Nadal, referring to the 15,000 empty seats that faced him at Rod Laver Arena.
Nadal, 34, will next play colourful Italian Fabio Fognini, who dismissed Australia's Alex De Minaur in straight sets.
Barty, the women's top seed, also said it was "very strange" to play behind closed doors, a day after more than 22,000 fans visited Melbourne Park.
Barty's straightforward 6-2, 6-4 win over Russia's Ekaterina Alexandrova put her into the fourth round without dropping a set as she bids to become the first Australian winner since Chris O'Neil in 1978.
"It's very strange, it changes the sound in the court a little bit," Barty said of the empty, 7,500-seat Margaret Court Arena.
"It kind of felt a little bit like practice," she added.
Players were ordered into a biosecure "bubble" during the lockdown, just the latest coronavirus disruption for a tournament that was pushed back three weeks to allow for quarantines.
The Australian Open, the biggest international sports event so far this year, is seen as a test case for the Tokyo 2020 Olympics, which are scheduled to start in July after a year's delay.
As play unfolded in the empty arenas, former world number one Karolina Pliskova had a racquet-smashing tantrum en route to a 7-5, 7-5 defeat by fellow Czech Karolina Muchova.
Ukrainian fifth seed Elina Svitolina beat Yulia Putintseva 6-4, 6-0, and Russia's men's fourth seed Medvedev overcame buttock pain and a mid-match lapse in his 6-3, 6-3, 4-6, 3-6, 6-0 win over Filip Krajinovic of Serbia.
"It's a different atmosphere, different vibe," said Greek world number six Tsitsipas, after his 6-4, 6-1, 6-1 win over Mikael Ymer.
"But if I can win my next matches, the crowd will be back. It's just five days, and I'll be happy to see them back."
Tsitsipas beat Ymer in a silent John Cain Arena -- which had been packed with thousands of noisy fans late on Friday for Australian player Nick Kyrgios's defeat by Dominic Thiem.
In the same venue, Matteo Berrettini beat Russian seed Karen Khachanov 7-6 (7/1), 7-6 (7/5), 7-6 (7/5) to set up a meeting with Tsitsipas.
"I really miss the crowd, I have to be honest," said the Italian.
"Looking at a stadium like this and seeing it empty is not the best feeling. But we're living in really tough times."
Elsewhere Russia's Rublev ended Spanish veteran Feliciano Lopez's record 75th consecutive Grand Slam to set up a meeting with Norway's Casper Ruud.