Novak Djokovic made a slice of Grand Slam history on his way into the Australian Open third round on Wednesday but last year's women's finalist Zheng Qinwen was knocked out in the biggest shock so far.

The normally ice cool "Queen Wen" got hot under the collar as she was sent packing 7-6 (7/3), 6-3 in the second round by world number 97 Laura Siegemund of Germany.

Seventh seed Zhengconverted six of her 11 break-point chances during a two hour 20-minute match.

Zheng Qinwen became the first Chinese player to win Olympic tennis singles gold when she defeated Croatia's Donna Vekic on Saturday, hailing her victory as a "proud" moment for herself and her country.

World number seven Zheng triumphed 6-2, 7-5 and will face either Croatia's Donna Vekic or Anna Karolina Schmiedlova of Slovakia in the gold medal match.

An authoritative Aryna Sabalenka blew China's Zheng Qinwen off court on Saturday to successfully defend her Australian Open title -- the first woman to do so in more than a decade.

The Belarusian world number two has yet to drop a set in Melbourne this year

Aryna Sabalenka has blown all-comers off court on her march to the final of the Australian Open and China's Zheng Qinwen will need to produce something extraordinary to deprive her of back-to-back titles on Rod Laver Arena on Saturday.

She is the first Chinese player since 2014 to reach the final at Melbourne Park.