MELBOURNE (AFP) -- Sixth seed Ons Jabeur and former champion Caroline Wozniacki fell victim to exciting young Russians in the Australian Open second round on Wednesday, Jan. 17, as Novak Djokovic prepared to resume his quest for a 25th Grand Slam title.

The veteran pair were no match for Mirra Andreeva and Maria Timofeeva, who emphatically stamped their mark on the opening Grand Slam of the year, which was marred by rain on day four.

But fourth seeds Coco Gauff and Jannik Sinner, along with home hope Alex de Minaur and world number 11 Barbora Krejcikova, had no trouble progressing.

Andreeva, just 16, was in scintillating form to take down 29-year-old three-time major runner-up Jabeur 6-0, 6-2 under the closed roof on Rod Laver Arena in just 54 minutes.

"Probably it was the best match (ever)," said Andreeva, a schoolgirl who burst onto the scene when she reached the fourth round at Wimbledon last year as a qualifier.

"The first set, I didn't expect that I would play this good. Second set was also not bad. So, yes, for me it was an amazing match."

Her reward is a third-round clash with France's Diane Parry.

Timofeeva, a 20-year-old qualifier, was equally impressive against 2018 champion Wozniacki, who flew through the first set and was a break up in the second.

Undeterred, Timofeeva, showing impressive power, hauled herself back into the contest and ultimately prevailed against a player 13 years her senior, winning 1-6, 6-4, 6-1.

"It was an honour to play here against Caroline today. I'm just beyond happy and couldn't ask for more," she said after setting up a testing third-round meeting with 10th seed Beatriz Haddad Maia.

With play on outside courts starting more than three hours late due to rain, Sinner was one of the fortunate few to be scheduled in one of the three main arenas, which all have roofs.

The Italian wasted no time in dispatching Dutch qualifier Jesper de Jong 6-2, 6-2, 6-2 on Margaret Court Arena.

His next assignment in his bid for a maiden Grand Slam title will be against Argentine 26th seed Sebastian Baez or Colombia's unseeded Daniel Elahi Galan.

US Open champion Gauff was equally untroubled in sweeping past fellow American Caroline Dolehide 7-6 (7/2), 6-2 while De Minaur and Krejcikova had easy straight-sets wins.

'It is what it is'

Djokovic headlines the night session on center court 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 match 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, 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 court ahead of Djokovic to face Czech 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.

Last year's finalist Stefanos Tsitsipas and fifth seed Andrey Rublev are also in action.