MELBOURNE - China's Li Na and Zheng Jie qualified for the third round at the Australian Open after Wednesday's matches while Venus Williams booked a showdown with in-form Maria Sharapova.

Zheng Jie of China reacts during her women's singles match against Samantha Stosur of Australia at the Australian Open tennis tournament in Melbourne, Jan 16, 2013. [Photo/Agencies]

Zheng overcame a 2-5 deficit in the deciding set to beat ninth-seeded Samantha Stosur 6-4, 1-6 and 7-5. The shattering defeat continued Stosur's horror run at her home Grand Slam. The 2011 US Open champion has never ventured beyond the fourth round in 11 visits to Melbourne, including a first-round trip last year.

Stosur appeared to have the match in the bag only to twice falter while trying to serve it out and then dropping serve for a third consecutive time to hand the world No 40 victory after two hours and 42 minutes.

Former Wimbledon semifinalist Zheng reeled off five straight games to snatch victory and set up a third-round clash on Friday with No 18 seed Julia Goerges.

"In the final set 2-5, I was thinking that the first time I played in center court is 2006. How many times I can play on court like this? I need to keep fighting and enjoy the match," said Zheng. "Just that simple. It's amazing that I can come back."

Sixth-seed Li Na survived a second-set scare to beat Belarusian Olga Govortsova 6-2, 7-5 to reach the third round for the consecutive year, including the 2011 final loss to Kim Clijsters.

Li started strongly and breezed through the first set in 32 minutes, dropping just two games and hitting a number of impressive forehand winners.

Govortsova showed some fight to break early in the second and built a 4-2 lead to force the Chinese number one into action.

Li Na of China hits a return to Olga Govortsova of Belarus during their women's singles match at the Australian Open tennis tournament in Melbourne, Jan 16, 2013. [Photo/Agencies]

The 30-year-old won five of the next six games to break her opponent's stubborn resistance and earn a place in the last 32.

Li faced two set points at 3-5 in the ninth game of the second set, but came back to level the set at 5-5 before breaking Govorsova's serve to clinch the match.

The 25th seed Venus Williams set up a third-round showdown with Russian Sharapova by beating France's Alize Cornet 6-3, 6-3.

Williams lost the first two games of the match and went down a break of serve early in the second set before outclassing Cornet, while second-seeded Sharapova became the first woman since 1985 to dole out consecutive double-bagels at a Grand Slam after hammering Japan's Misaki Doi 6-0, 6-0 in 47 minutes, two days after her opening victory against fellow Russian Olga Puchkova.

Williams and Sharapova have 11 Grand Slam singles titles between them.

Defending champion Novak Djokovic was in the zone with a dazzling demolition of Ryan Harrison as he outclassed the young American 6-1, 6-2, 6-3.

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