Rafael Nadal put his old rival Fabio Fognini to the sword to reach the Australian Open quarter-finals and move within three wins of the all-time Grand Slam titles record on Monday.

The Spanish great was 1-1 with the flamboyant Italian in Grand Slams but he was never seriously troubled in his 6-3, 6-4, 6-2 win on Rod Laver Arena.

Nadal is now into his 43rd Grand Slam quarter-final, staying on course for a title match with eight-time winner Novak Djokovic who battled through an abdominal injury to reach the last eight on Sunday.

"I'm happy to be in the quarter-finals today -- that means a lot to me, it's positive stuff," said Nadal, who is targeting a record 21st men's Grand Slam singles crown.

Next up for Nadal is Greece's world number six Stefanos Tsitsipas, who went through on a walkover after Italy's Matteo Berrettini pulled out with an abdominal strain.

The Melbourne tournament remained fan-free for a third day on Monday during a five-day lockdown in Victoria state to curb a coronavirus outbreak.

As the action continued in front of empty stands, unseeded American Jessica Pegula reached her maiden Grand Slam quarter-final with victory over Elina Svitolina, her first over a top-10 player.

Pegula, whose billionaire father owns the Buffalo Bills NFL team, overcame fifth seed Svitolina 6-4, 3-6, 6-3 to set up a meeting with fellow American Jennifer Brady, a 6-1, 7-5 winner against Croatia's Donna Vekic.

"I can't get more confident -- it is my best result yet and I'm playing good tennis and today was a hard-fought win," said Pegula, 26. "Jen (Brady) is an awesome person. She's a great person," Pegula added. "She was texting me, 'I'm so happy, I'm so proud. This is awesome.'"

Russians are coming

Elsewhere, fourth seed Daniil Medvedev and seventh seed Andrey Rublev both won to ensure an all-Russian quarter-final.

Medvedev, the 2019 US Open runner-up, blew away American world number 192 Mackenzie McDonald 6-4, 6-2, 6-3 to extend his winning streak to 18 matches.

Rublev, who is also unbeaten this year, went through when Norway's Casper Ruud retired after losing the first two sets.

The 22-year-old Norwegian had reached the last 16 at a Slam for the first time -- emulating his father, Christian, who achieved the same feat at the 1997 Australian Open.

With qualifier Aslan Karatsev already through to face Grigor Dimitrov in the top half of the draw, it means there will be three Russian men in the last eight of a Slam for the first time since the Open era began in 1968.

Later, Australia's world number one Ashleigh Barty will look to advance to the quarter-finals at the expense of unseeded American Shelby Rogers when they open the evening session on Rod Laver Arena.

Barty is a model of consistency, having reached at least the fourth round at every Slam she has played since first making the second week of a major at the 2018 US Open.

Her smooth progress so far has lifted hopes of a first Australian winner in Melbourne since Chris O'Neil won the women's title in 1978.

If Barty wins she will face either Elise Mertens of Belgium or Karolina Muchova of the Czech Republic, who feature on the neighbouring Margaret Court Arena.