Two-time champion Petra Kvitova and former winner Maria Sharapova both suffered surprise defeats in the first round of the women’s singles at Wimbledon.

Eighth seed Kvitova never looked comfortable against world number 50 Aliaksandra Sasnovich of Belarus, who won 6-4 4-6 6-0.

Qualifier Vitalia Diatchenko came from a set and 5-2 down to defeat Sharapova.

The world number 132 battled back to win 6-7 (3-7) 7-6 (7-3) 6-4.

Sixth seed Caroline Garcia from France also went out after a 7-6 (7-2) 6-3 defeat by Switzerland’s Belinda Bencic.

But last year’s winner Garbine Muguruza made a solid start to the defence of her title with a 6-2 7-5 win over British wildcard Naomi Broady.

There was also an easy win for top seed Simona Halep, who beat Japan’s Kurumi Nara 6-2 6-3.

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Kvitova has now gone out before the quarter-finals in five of her six Grand Slam appearances since returning to action after the stabbing that left her with severe lacerations to her playing hand in 2016.

“I’m sad. I wanted to win very badly, maybe too much. The nerves were there again. I just tried to kind of fight with myself,” she said.

“I was the biggest opponent I could have. I didn’t really have a clear mind. I was thinking a little bit too much.

“Probably at Wimbledon it’s a little bit more than the other Grand Slams because obviously I know I can play well.

“But it is how it is. I think the worst pressure is in the first rounds, second rounds, and third rounds. After that it’s fine.”

Sharapova, back at SW19 after a two-year absence, served 10 double faults in her match against her fellow Russian, including the final point of the match.

As well as missing her chances in set two, the 2004 champion was twice a break up in the deciding set as Diatchenko needed treatment from the trainer on a back problem.

It was Sharapova’s first-ever defeat in the opening round of Wimbledon.

Good start for Muguruza

Spain’s Muguruza, the third seed this year, is bidding to make her third Wimbledon final after also reaching the decider in 2015.

Broady, the British number four ranked 138th in the world, looked nervous initially on her Centre Court debut.

She made more of a fight of it in the second set but Muguruza was too strong.

“I’m back. It’s always good, I’m thinking to win and actually enjoy this time more,” Muguruza told BBC Sport.

“I’m pretty happy with my serve and controlling the emotions. To be back in a Grand Slam is always difficult, so I’m excited with the way I’m playing.”

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