Osaka romps as Halep and Raonic battle through Open epics

Top seed Simona Halep was forced to dig deep to stay in the Australian Open on a day of epic battles Thursday that saw Japanese pair Naomi Osaka and Kei Nishikori survive but 2014 champion Stan Wawrinka crash out.

The world number one Romanian staggered through against American Sofia Kenin 6-3 6-7 (5/7) 6-4, but it was far from convincing and her second three-set test in a row.

"I have no idea how I won this tonight, it's so tough to explain what happened on court," said the French Open champion, who now meets Venus Williams after the 38-year-old rolled back the years to beat France's Alize Cornet.

In another titanic battle, Canadian Milos Raonic ousted Wawrinka in four tightly-contested sets that all went to tie-breaks, while Nishikori was stretched to a draining five sets against Ivo Karlovic before sinking to his knees in relief.

Seventh seed Dominic Thiem limped out when he retired while losing 7-5 6-4 2-0 to young Australian wildcard Alexei Popyrin.

Thiem went through a first round five-setter against Benoit Paire that finished in the early hours of Wednesday morning and he never looked 100 per cent.

US Open champion and fourth seed Osaka had it much easier, sweeping past Slovenia's Tamara Zidansek 6-2 6-4 with the roof closed on Margaret Court Arena after rain interrupted the opening major of the year.

The 21-year-old's breakthrough at Flushing Meadow over Serena Williams made her a new standard bearer for tennis in her homeland, Asia and the next generation of women, and she is working hard on living up to the hype.

- Energy-sapping -
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