Stars struggle at the Australian Open

Hampered by a niggling knee problem, Romanian Simona Halep was the biggest casualty on the first day of the Australian Open as she lost 6-3, 6-1 to American Shelby Rogers.

Halep, ranked fourth at Melbourne Park, became the first seed to be bundled out of the season-opening Grand Slam, falling to the power-hitting American in 75 minutes.

She sought medical advice after the first set and was seen flexing her left knee throughout the second.

"I had pain in my knee," said Halep.

"For me, in the second set, was difficult to move, but she deserved to win.

"She was aggressive and she hit very strong."

Halep said she had been battling the problem since the WTA Tour Finals in Singapore.

She had no issues during the off-season, but it flared up again in Shenzhen two weeks ago and she had been trying to control the pain since.

"I had some anti-inflammatory (medication) before the match and the previous days," she said.

"I can play about 45, 50 minutes without pain. And then it comes. Today, it was about 5-3 in the first set, so then it was tough to fight... And I couldn't do what I wanted.

"I have not seen the doctor yet. I need an MRI. Probably need some time off to recover, because it's difficult to play with the pain."

World No. 1 Andy Murray was tested and Stan Wawrinka lost his cool as stars struggled on a hot first day at the Australian Open yesterday.

Roger Federer and Angelique Kerber, the defending women's champion, both dropped a set on a day which threatened a host of upsets at Melbourne Park.

Wawrinka drew gasps as he smashed a volley straight at a static Martin Klizan deep in the fifth set, en route to a difficult 4-6, 6-4, 7-5, 4-6, 6-4 win.

"I stopped playing. He could play anywhere, the whole court," a perplexed Klizan said.

"He could play anywhere on the court and he hit me."

As afternoon temperatures topped 32 deg C, Murray came through a 2hr 47min test against Ukraine's Illya Marchenko 7-5, 7-6 (7/5), 6-2.

He fared better than Kei Nishikori and Marin Cilic, who were both taken to five sets by their opponents.

Nishikori, who said that he is primed to win his first Major title this year, came through a five-set battle with Russia's Andrey Kuznetsov 5-7, 6-1, 6-4, 6-7 (6/8), 6-2.

Cilic, the 2014 US Open winner, came from two sets down to dispatch Jerzy Janowicz 4-6, 4-6, 6-2, 6-2, 6-3.

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Former world No. 1 Federer was also stretched by Austria's Juergen Melzer before winning 7-5, 3-6, 6-2, 6-2.

"Any match is a good match," said the 35-year-old Swiss, who missed the second half of 2016 with a knee injury.

"Even if I had lost today, it would have been good because I'm back on the court."

Kerber, defending a Grand Slam title for the first time, laboured past Ukraine's Lesia Tsurenko 6-2, 5-7, 6-2 in an unconvincing performance.

The German was an early loser at both of her warm-up tournaments and she took time to settle against Tsurenko.

But she also started slowly last year, when she had to save a match-point against Japan's Misaki Doi in the first round.

"The first round is always tough. I'm just trying to enjoy it and I'm so, so happy to be in the second round," Kerber said.

Venus Williams, the oldest player in the women's draw at 36, also found herself with a fight on her hands, but she came through 7-6 (7/5), 7-5 against 22-year-old Kateryna Kozlova.

"Girl, I don't know," she told on-court interviewer Samantha Smith, who pointed out that Williams turned professional in 1994, the year that Kozlova was born.

"I know how to play tennis. I like to think I'm good at this.

"She hasn't had the years that I've had yet, the grey hairs and I'm dying, I guess. The wrinkles that I'm hiding... You're trying to make me feel old."

China's Zhang Shuai, who made a surprise run to last year's quarter-finals, had an easier time with a 6-0, 6-3 win over Aliaksandra Sasnovich of Belarus.

Canada's Eugenie Bouchard continued her recent resurgence with a 6-0, 6-4 win over Louisa Chirico. - AFP