Australian Open news 2020 - Daniil Medvedev v Alexei Popyrin: LIVE

Medvedev, a US Open finalist last year, was up by a set and a break when local hope Popyrin took a medical timeout for a problem with his left hip.

Popyrin, ranked 96 in the world, was unable to put up much of a challenge as Medvedev converted five of his eight breakpoints while facing just one on his own serve.

"(It) was a good match. I didn't lose my serve... That's the most important in matches in Grand Slams, to try to hold your serve easy, to make your job easier," said Medvedev, who reached the fourth round for a second consecutive year at Melbourne Park.

Coming off a season featuring four titles and a Tour-leading 59 match wins, Medvedev has continued his good work at the year's first Grand Slam and had 19 unforced errors on Saturday compared with the 44 committed by Popyrin.

The 23-year-old Russian also won 15 of his 16 net approaches, including the one he volleyed to finish the match.

Next up for him will be a clash with three-times Grand Slam winner Stan Wawrinka, who advanced after American John Isner retired with an injury while trailing 6-4 4-1.

"Stan is a big hitter, great serves," Medvedev said of the Swiss 15th seed, the title winner at Melbourne Park in 2014.

"I'm going to work a little bit on return, maybe will work just to be aggressive myself, to not let him have all the time he wants because that's when he's the most dangerous."