Kei Nishikori celebrates winning his round two men's singles match against Ivo Karlovic at the Australian Open. Photo: Lynn Bo Bo/EPA

MELBOURNE – Japanese star Kei Nishikori battled through a draining five-set epic to make the Australian Open third round Thursday as Elina Svitolina and Karolina Pliskova kept their dreams of a maiden Grand Slam title alive.

Asia's top-ranked men's player needed an energy-sapping 3hr 48min to get past big-serving Croat Ivo Karlovic 6-3, 7-6 (8/6), 5-7, 5-7, 7-6 (10/7) in humid conditions on Margaret Court Arena.

“It was a tough match which could have gone both ways. He almost had it for sure,” said Nishikori, a three-time quarter-finalist at Melbourne Park, after falling to his knees in relief.

He next plays either 32nd seed Philipp Kohlschreiber or Joao Sousa.

Despite being seeded six and seven respectively, neither Svitolina, nor Pliskova has progressed further than the last eight at the Australian Open.

But self-assured Svitolina is bubbling with confidence after dismantling Viktoria Kuzmova 6-4, 6-1, while Pliskova woke up after losing the first set to race past Madison Brengle 4-6, 6-1, 6-0.

They were in action ahead of 23-time major winner Serena Williams who plays Eugenie Bouchard later, while six-time champion Novak Djokovic turns back the clock in a night match with Jo-Wilfried Tsonga on Rod Laver Arena.

World number one Simona Halep, who narrowly survived a first-round scare, is also back on court against American Sofia Kenin, who won the warm-up Hobart International and is on a six-match win streak.

Ukraine's Svitolina scored her biggest career win by clinching the WTA Finals in Singapore last October, and is ready to take the next step.

“It definitely brought me lots of confidence and showed I can play at a really high level,” she said. ”So I'm just trying to transfer this to the Grand Slam.”

A quarter-finalist in Melbourne last year, she next plays either Czech Kristyna Pliskova - identical twin sister of Karolina - or Zhang Shuai of China.

Elina Svitolina celebrates after defeating Viktoria Kuzmova during their women's singles match on day four of the Australian Open. Photo: David Crosling/EPA
Elina Svitolina celebrates after defeating Viktoria Kuzmova during their women's singles match on day four of the Australian Open. Photo: David Crosling/EPA

Karolina Pliskova's best Slam effort so far was the US Open in 2016, where she made the final and lost to Angelique Kerber.

She has made the quarters in her last two Australian Open appearances and entered this year's tournament on a high after winning the Brisbane International.

“The match had a bit of everything, some breaks, some good tennis, some bad mistakes from me too,” said the Czech of her win over Brengle.

Other women through included Italy's Camila Giorgi, who plays Karolina Pliskova next, and China's impressive 21st seed Wang Qiang, who earned a clash with Latvia's 13th seed Anastasija Sevastova. 

Belgium's 12th seed Elise Mertens lined up a third round showdown with American Madison Keys, seeded 17.

Doesn't quit

In her first tour match since losing a US Open final mired in controversy, Williams delivered an ominous warning in her 49-minute opening round thrashing of Tatjana Maria.

Next in the firing line is Canadian Bouchard. 

Williams, who is bidding to match Margaret Court's record of 24 Grand Slam crowns on her first return to Melbourne Park since winning in 2017, cited her consistency and few unforced errors as key takeaways from her first round outing.

Despite 2014 Wimbledon finalist Bouchard slipping down the rankings to 79, she said she was not taking her lightly.

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“It will be a great match. She plays really well. She does everything well, and I really like that she doesn't quit,” she said.

Djokovic, gunning for a record seventh title, has a fairytale meeting with Frenchman Tsonga in a rematch of their 2008 final that the Serb won.

“He also struggled with injuries lately. It's good to see him playing well. It's good to see him back,” the Serb said.

Men's fourth seed Alexander Zverev, who beat Djokovic to win the ATP Finals at the end of last season, takes on Jeremy Chardy while Open champion Naomi Osaka faces Slovenia's Tamara Zidansek.

Agence France-Presse (AFP)