Zheng stunned, Djokovic and Sabalenka battle through at Australian Open

Zheng Qinwen was the first big name to exit the women's draw at the Australian Open on Wednesday after the Olympic champion was stunned by Laura Siegemund while top seed Aryna Sabalenka made heavy weather of her second-round match before going through.

Novak Djokovic took another big step towards a record 25th Grand Slam title, and his 11th at Melbourne Park, with a four-sets win over Portuguese qualifier Jaime Faria after Carlos Alcaraz served up another quick-fire win to advance.

Twice champion Naomi Osaka rallied past Karolina Muchova to book a clash with Tokyo Olympics champion Belinda Bencic after a brief spell of rain delayed proceedings on the outer courts on the fourth day and returned in the afternoon.

China's Zheng had been bidding to emulate compatriot Li Na's 2014 triumph at Melbourne Park but her hopes evaporated on John Cain Arena where unseeded German Siegemund pulled off a stunning 7-6(3) 6-3 victory.

The fifth seed left the court looking like she was about to burst into tears while world number 97 Siegemund was beaming from ear to ear after a famous win.

Her fellow Paris Olympics gold medallist Djokovic, who was taking the court for his 430th Grand Slam match, was stung into action when Faria won the second set tiebreak.

"I think I responded well in the third set and particularly the fourth," said Djokovic.

"He was playing lights-out tennis at the end of the second set and start of the third and I had to weather the storm."

SMOOTH SAILING

Sabalenka is bidding to become the first woman to claim three straight titles at Melbourne Park since Martina Hingis from 1997-99 and while the Belarusian beat Jessica Bouzas Maneiro 6-3 7-5, it was far from smooth sailing.

After easing through the first two games on Rod Laver Arena, Sabalenka twice swapped breaks with the world number 54, before taking complete control for a 5-2 lead and closing out the opening set on serve.

The three-times Grand Slam champion's serve came under intense pressure in the next set and she found herself trailing 4-1 as an inspired Bouzas Maneiro began hitting stinging winners on both sides of the court.

Sabalenka found a spark from somewhere and fought back from 5-2 to level at 5-5 and fired a backhand winner to break again in the next game before wrapping up the contest to extend her win streak at the hardcourt major to 16.

Alcaraz had a far easier outing as the third seed hit 14 aces during a 6-0 6-1 6-4 win over Yoshihito Nishioka, whose Japanese compatriot Osaka rallied past Muchova 1-6 6-1 6-3.

American seventh seed Jessica Pegula defeated Belgian Elise Mertens 6-4 6-2 on Margaret Court Arena, while Bencic beat Suzan Lamens 6-1 7-6(3) and Olga Danilovic stunned 25th seed Liudmila Samsonova 6-1 6-2.