Nick Kyrgios put behind "17 hours a day" in bed with Covid to set up a blockbuster second-round showdown with tournament favourite Daniil Medvedev at the Australian Open on Tuesday.

The unpredictable Australian breezed through a straight-sets win over Britain's Liam Broady 6-4, 6-4, 6-3 in 1hr 54mn amid mayhem generated by his boisterous fans inside John Cain Arena.

The victory set up a clash with world number two Medvedev, who won his opening-round match against Henri Laaksonen.

It was a troubled build-up to his home tournament for the colourful Kyrgios after he came down with Covid-19, following a bad case of asthma, just before the Grand Slam.

There was doubt he would even make it to Melbourne Park, but in his first match since September he showed little effect of the inactivity and illness.

"When I tested positive it wasn't great news a week out from the Australian Open, I had some doubts about whether I would actually be playing," Kyrgios said on court.

"I isolated and I was lucky enough to have a tennis court to practise on. I served really well today, I'm just happy to be here again."

Kyrgios said he was bed-ridden with the virus for "17 hours" a day for the first couple of days.

"I was obviously concerned that I wouldn't be physically ready to play, I took it day by day and I'm just so pumped to be here in my first match of the year, on my most favourite court in the entire world."

Hus dynamic serve was on song. He won 81 percent of first-serve points, hit 21 aces, 41 winners and broke Broady's service four times.

Kyrgios played only eight events last year, after taking part in just three in the previous year, with his world ranking sliding to 115 after being as high as 13 in October 2016.

The win ended a five-match losing sequence for Kyrgios, whose previous win was against Kevin Anderson in Atlanta last year.