Australian Open 2018: Garbine Muguruza loses to Hsieh Su-wei, Simona Halep wins

Garbine Muguruza won the French Open in 2016 and Wimbledon last year

Garbine Muguruza was beaten in straight sets by world number 88 Hsieh Su-wei in the Australian Open second round.

The Wimbledon champion, seeded third, struggled physically as temperatures soared in Melbourne and had treatment to her left foot in the first set.

Taiwanese player Hsieh, 32 - who won 7-6 (7-1) 6-4 - will play 26th seed Agnieszka Radwanska in the third round.

Meanwhile, top seed Simona Halep beat Eugenie Bouchard 6-2 6-2 in an hour and seven minutes despite playing in pain.

The 26-year-old Romanian world number one, seeking her first Grand Slam title, turned her ankle in her first-round win over Destanee Aiava.

"I feel pain but I didn't think about it. I just wanted to play the match," said the two-time Melbourne quarter-finalist, who faces unseeded American Lauren Davis in the third round on Saturday.

Canadian Bouchard, the 2014 Wimbledon runner-up who beat Halep in the semi-finals at the All England Club that year, is now ranked 112 and only held her serve once.

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Spaniard Muguruza, 24, came from 5-2 down against Hsieh to force a first-set tie-break but eventually lost in straight sets.

The two-time Grand Slam champion also fell 5-2 behind in the second set and threatened a comeback as she broke serve and saved a match point but Hsieh served out for victory at the second attempt.

Muguruza has struggled for fitness in the early weeks of the season and began the match with strapping on her foot.

"I maybe could have done things better but at the end, she deserves to win," she said.

"It's blisters at the end. I think the surface of the court, I don't know how much heat, it's terrible, very, very hot, and it's easy to get blisters and red."