PARIS • World No. 1 Naomi Osaka said she had been suffering from headaches because of the stress of being top seed at a Grand Slam for the first time and admitted that her shock exit from Roland Garros was "the best thing" that could have happened to her.

The 21-year-old's hopes of winning a third successive Grand Slam title ended yesterday when she was knocked out of the French Open in the third round by the unheralded Katerina Siniakova.

The reigning US and Australian Open champion crashed to a 6-4, 6-2 loss to the 42nd-ranked Czech and ended a 16-match winning streak in Grand Slams.

The Japanese was undone by a shocking 38 unforced errors as she finally ran out of luck in Paris, having had to come back from a set and a break down in her first two matches.

"Losing is probably the best thing that could have happened," she said. "I felt very tired. In the other matches I had headaches, maybe that's the stress. I felt there was a weight on me. This hasn't been the happiest of times. I don't want to say I was depressed - that's too strong a statement.

"On a disappointment level of 1-10 - I am probably at a 100 at the moment."

Osaka also admitted that she had been "overthinking" her game and her ambitions.

"I was overthinking this calendar Grand Slam thing. It's something I wanted to do forever but, if it was that easy, everybody would have done it," she said.

"I have to work hard now to put myself in the position to do it again."

Osaka dropped the first set for the third straight match, squandering seven break points and Siniakova, the world's No. 1 doubles player and the women's doubles champion in Paris last year alongside Barbora Krejcikova, made her pay.

Despite being the top seed, Osaka flattered to deceive in Paris. She was two points away from defeat in the first round against Anna Karolina Schmiedlova and came back from a set and break down to see off Victoria Azarenka in the second round.

Tennis great Martina Navratilova believes that Osaka needs to learn to get to grips with playing on clay.

"She struggled in her first two matches," Navratilova told Tennis Channel. "She still doesn't quite have the instinct of what to do on clay. She was zero from seven on break points in the first set... It's still a matter of learning how to play on clay and what shots to hit."

In yesterday's other matches, defending champion Simona Halep stormed into the fourth round after defeating Lesia Tsurenko of Ukraine 6-2, 6-1 in just 55 minutes.

In the men's draw, German fifth seed Alexander Zverev beat Serbia's Dusan Lajovic 6-4, 6-2, 4-6, 1-6, 6-2 to reach the last 16.

Sixth seed Stefanos Tsitsipas became the first Greek player in 83 years to reach the second week at Roland Garros after he defeated Serbia's Filip Krajinovic 7-5, 6-3, 6-7 (5-7), 7-6 (8-6).

World No. 1 Novak Djokovic, meanwhile, eased into the last 16 to step up his bid to hold all four Grand Slam titles simultaneously for the second time.

The Serb saw off unseeded Italian Salvatore Caruso 6-3, 6-3, 6-2.

REUTERS, AGENCE FRANCE-PRESSE

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