China's Zheng Qinwen and women's two-time defending champion Arnya Sabalenka recorded battling first round wins, while men's second seed Alexander Zverev produced a commanding performance at the Australian Open on Sunday.

Storms wreaked havoc on the tournament's opening day, with heavy rain and thunder forcing outside matches to be suspended for more than six hours.

Aryna Sabalenka hits a return during the women's singles first round match between Aryna Sabalenka of Belarus and Sloane Stephens of the United States at Australian Open tennis tournament in Melbourne, Australia, Jan. 12, 2025. (Photo by Chu Chen/Xinhua)

Matches had to be played indoors and under a retractable roof at the tournament's three main stadiums - the Rod Laver Arena, Margaret Court Arena and John Cain Arena.

Fifth seed Zheng enjoyed being in the climate-controlled Rod Laver Arena, but was faced with a challenge from Romanian qualifier Anca Todoni before pulling out a 7-6 (3), 6-1 victory in almost two hours.

She led 5-3 in the opening set but failed to convert five set points across the next two games. 20-year-old Todoni had three set points in the 12th game, before a composed Zheng lifted to dominate the tiebreak and then raced through the second set.

Zheng, last year's tournament finalist, closed out the match with her eighth ace before pumping a fist and letting out a roar to celebrate her successful start in the year's opening Grand Slam.

Paris Olympic champion Zheng had not played since the season-ending WTA Finals in early November, when she had lost the final to Coco Gauff.

She withdrew from China's squad at the mixed teams United Cup, prioritising rest ahead of the Australian Open.

The 22-year-old is hoping to build on her performance when she meets either Laura Siegemund or Hailey Baptiste in the second round.

"The first round match is always not easy, especially that she is playing well," said Zheng, who hit 29 winners. "But I'm happy to get through the match and I found my rhythm."

It was not good news for compatriot Wang Xinyu after she lost to 11th seed Paula Badosa in straight sets. 37th seed Wang was gallant, but had 40 unforced errors and Badosa capitalised to win 6-3, 7-6 (5).

In the night session at Rod Laver Arena, Sabalenka beat former US Open champion Sloane Stephens 6-3, 6-2 to successfully start her bid for a third straight title at Melbourne Park.

Swiss tennis legend Martina Hingis is the last women's player to achieve the feat after she won three in succession at the Australian Open from 1997 to 1999.

Sabalenka had several lapses in the match, but she showcased her ferocious groundstrokes with 20 winners. She will play Spain's Jessica Bouzas Maneiro in the second round.

"It was a tough match, always tough matches against her," said Sabalenka, who rolled to victory in 77 minutes. "It's not like I played my best, but I was glad I was able to close it out in straight sets."

In the men's draw, China's rising star Buyunchaokete suffered a straight sets defeat to qualifier Hady Habib in a first round upset.

The 219th ranked Habib served strongly and overcame a late rally from Buyunchaokete to record a 7-6 (4), 6-4, 7-6 (6) victory in two hours and 31 minutes.

In the night session, Zverev unfurled several spectacular winners to easily dispatch 103rd ranked Lucas Pouille 6-4, 6-4, 6-4 in two hours and 21 minutes.

Earlier, sixth seed Casper Ruud and Japanese veteran Kei Nishikori survived five-set marathons.

Ruud, a three-time Grand Slam finalist, outlasted Spain's Jaume Munar 6-3, 1-6, 7-5, 2-6, 6-1 in a shaky opening performance. "It was just a really tough match," he said.

Former US Open finalist Nishikori came back from the brink, saving two match points, to beat Brazil's Thiago Monteiro 4-6, 6-7 (4), 7-5, 6-2, 6-3.

Day two action on Monday will be highlighted by defending champion Jannik Sinner, third seed Carlos Alcaraz and 10-time tournament winner Novak Djokovic, arguably the top men's title contenders, kick-starting their campaigns.

Women's second seed Iga Swiatek, four-time Grand Slam champion Naomi Osaka and former US Open winner Coco Gauff will also feature.