By Shrivathsa Sridhar MELBOURNE (Reuters) -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.

Thunderstorms lashed Melbourne Park on the opening day of the Australian Open but fifth seed Zheng Qinwen safely reached round two.

Last year's runner-up Zheng Qinwen was knocked out of the Australian Open on Wednesday in the biggest shock so far but defending champion Aryna Sabalenka and two-time winner Naomi Osaka

Organisers cancelled five singles matches as persistent rain washed out a large chunk of play on the opening day of the Australian Open on Sunday,

Last year's runner-up Zheng Qinwen was knocked out of the Australian Open on Wednesday in the biggest shock so far while defending champion Aryna Sabalenka had to battle serve jitters to make the third round.