MELBOURNE (AFP) -- Novak Djokovic resumes his quest for a 25th Grand Slam title on Wednesday, Jan. 17, against home hope Alexei Popyrin, while fellow defending champion Aryna Sabalenka faces her second consecutive qualifier.

Serbian superstar Djokovic dropped a set against unheralded Croat Dino Prizmic in his opening clash and will not want to do repeat the feat against 43rd-ranked Popyrin.

But the 10-time Australian Open winner heads into the night match on Rod Laver Arena with lingering concerns over his health after admitting he was "a bit under the weather" against Prizmic.

"Look, it is what it is. You just have to try to deal with it and get over it and accept the circumstances and try to make the most of it," he said.

Should he come through against the Australian, the world number one will face a third-round clash against veteran Frenchman Gael Monfils or Argentine Tomas Martin Etcheverry, who ended Andy Murray's tournament.

Sabalenka will be on center court ahead of Djokovic to face Czech qualifier Brenda Fruhvirtova.

The powerful Belarusian second seed dropped just one game in obliterating her first-round opponent, with Fruhvirtova set to face more of her wrath.

Men's fourth seed Jannik Sinner is also in action, against Dutchman Jesper de Jong on Margaret Court Arena as he looks to maintain his recent impressive form, which has included a win over Djokovic.

US Open champion Coco Gauff, who romped through her first match, will follow on from Sinner against fellow American Caroline Dolehide in her quest for a maiden title at Melbourne Park.

Men's seventh seed Stefanos Tsitsipas, last year's losing finalist, meets Australian Jordan Thompson, but is not worried about a hostile crowd, with a big Greek contingent in Melbourne.

"I know I have a great fan base, I have a great crowd by my side. This gives me belief, this gives me an additional type of confidence that is not typically there on other tournaments," he said.

Other players in action include women's sixth seed Ons Jabeur against exciting Russian 16-year-old Mirra Andreeva, former champion Caroline Wozniacki, and men's fifth seed Andrey Rublev.