Serena Williams and Anastasija Sevastova seek spot in US Open final

Naomi Osaka US Open

That was at Wimbledon in 1995, and both Shuzo Matsuoka and Kimiko Date lost in that round.

A tactical switch enabled and a shift in momentum enabled seventh-seeded Cilic to dominate the fourth set, giving up just four points on serve to send the contest into a deciding set.

As Nishikori began to find his rhythm Cilic started to misfire and the Japanese 21st seed collecting a second consecutive break on a double fault to surge in front 5-4 before holding serve to level the match.

But Cilic, US Open champion in 2014 refused to back down and took the match into a decider by winning the fourth set 6-4.

The No. 14 seed was last year's US Open runner-up, losing to Stephens in the final, the only Grand Slam final appearance of her career.

Sevastova looks to be in deep trouble from the get-go, because she's never felt the weight of Williams' shots or the unrelenting pressure her aggressive play applie.

"I think it's because of Kei", she said, holding her hands apart to show how much bigger Nishikori is in Japan, from where her family moved to NY when she was 3.

'I'm just really grateful that she's playing again.

The Latvian made her third consecutive trip to the NY quarter-finals this year and knocked defending champion Sloane Stephens out to reach her first Grand Slam semi-final.

Osaka, who is just 20 years old, is having a terrific 2018 season.

Osaka said she has tried to keep this tournament business-like as she navigates her way through the draw, but her triumph in NY is not just about advancing her career.

"Today was not my day, obviously", Tsurenko said. "I was not feeling well", she said. In her third-round match, she was even quicker, dominating Aliaksandra Sasnovich, 6-0, 6-0, in 50 minutes. With Suarez Navarro serving, the Spaniard took a 30-0 lead, but after a service error allowed Keys back in, she fought back to win a second set point and take the set, 6-4.

Tsurenko laboured in the heat during her fourth-round victory over Marketa Vondrousova, having her temperature and blood checked during a medical timeout in the first set and almost quitting when she trailed early in the second. She recovered to win in three sets, with her opponent accusing her after the match of acting.

It was another hot afternoon Wednesday, with temperatures in the high-80s (30s Celsius) but feeling some 10 degrees hotter with the humidity.

On Wednesday, Osaka only needed 12 winners because a whopping 31 of her other points came via unforced errors by Tsurenko.

"I hate matches like this", said Tsurenko.

The 23-year-old thinks she is more equipped than ever to deal with important moments on important stages.

" She's definitely someone that gets a lot of balls back and something I have to be ready for."
She won 20 of her 22 first serves, and she broke Tsurenko's serve five times.

The Japanese stars both advanced to the semi-finals at Flushing Meadows on Thursday (AEST).