Naomi Osaka says the pressure of expectation after her US Open win is causing her “stress” as the Japanese world number six tries to “prove” herself.

The 20-year-old’s first Grand Slam win earlier this month was overshadowed by Serena Williams’ row with the umpire.

“I think definitely as the weeks go by, I have this feeling of wanting to prove myself,” said Osaka.

“I think that takes a toll a little bit because I stress myself out.”

Osaka missed out on becoming the first player in 2018 to reach three consecutive finals, losing 6-4 6-4 to Latvia’s Anastasija Sevastova in the semi-finals of the China Open in Beijing.

An emotional Osaka apologised to opponent Zhang Shuai after her quarter-final win over the Chinese a day earlier, having been close to tears at points during the match on Friday.

“If you don’t win a tournament, then people will say, ‘Oh, she hasn’t won a tournament.’ If you haven’t won a Slam, they’ll say, ‘She hasn’t won a Slam,'” added Osaka.

“Then if you win one Grand Slam, they’re like, ‘Oh, she only won one Grand Slam.’

“I know it’s bad, but I sort of read the comments. I’m just like, ‘Oh, I guess I have to do more, to be better.'”

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Against world number 20 Sevastova, Osaka was broken once in the first set to concede the opener in 46 minutes.

Sevastova broke again for a 4-2 lead in the second set against a visibly struggling Osaka, who was complaining of a back injury.

The world number six briefly rallied after a medical timeout and drew level at 4-4 with a break of her own.

But Sevastova reclaimed the break before sealing victory in 91 minutes on her first match point.

“Naomi is one of the best players this year so you need to be aggressive and concentrate,” said Sevastova, who will play world number two Caroline Wozniacki in the final.

Wozniacki beat Chinese wildcard Wang Qiang 6-1 6-3 in 82 minutes.

“I was focused and I stayed focused. She has been winning a lot of matches recently and I knew it was going to be a very tough match,” said Wozniacki.

Australian Open champion Wozniacki took an early 2-0 lead before pulling further clear with another break to seal the first set in 37 minutes.

The Dane also grabbed an early break at the start of the second, but this time Wang responded to lead 3-2.

Wozniacki broke back for a 4-3 lead before wrapping up the win with another break of the Wang serve.