The U.S. Open champion responded by conceding only five points in the next set on her way to a 3-6, 6-0, 6-4 win Thursday that secured her spot in the Brisbane International semifinals.

Kei Nishikori worked his own way out of a jam against 2017 champion Grigor Dimitrov when he was down a break in the second set of their quarterfinal match, winning six of the last seven games to clinch it 7-5, 7-5.

And so after the back-to-back matches on Pat Rafter Arena, two players from Japan, both seeded No. 2, were into the semifinals.

Osaka was clearly under pressure against the eighth-seeded Sevastova, who had won both of their head-to-head meetings last year and converted two service breaks in the first set.

A disconsolate-looking Osaka went to a courtside chair at the changeover. And whatever coach Sascha Bajin told her during a quick, animated conference, it worked.

She finished with 11 aces, converted all four of her break-point chances in the second and third sets and appeared far more confident in her own game.

Bajin, a former hitting partner for Serena Williams, really just gave her a reality check. He told Osaka to stay calm and wait for her opportunities.

“She’s one of the best players in the world. I just have to stay in there, and hopefully I’ll get a chance,’” Osaka said. “I did, so I just kept trying to roll with it. He literally told me that.”

On-court coaching is allowed at WTA events, but it is banned at Grand Slam tournaments.

The 21-year-old Osaka will play Lesia Tsurenko, a 7-5, 6-3 winner over Anett Kontaveit, in the semifinals. She could rise to No. 3 in the rankings next week — which would be a record high for a player from Japan.

Osaka has now made the semifinals or better at four of her last five tournaments, a streak that began with her run to a first major title that culminated with a memorable win over Williams in the U.S. Open final. And it has all been a significant boost to her confidence ahead of the Australian Open, which starts on Jan. 14.

“I feel like right now I’m really confident in myself, and I feel like the offseason training that I’ve been doing is really paying off,” she said. “And I’m not sure if I would have had the same feeling six months ago. Six months ago I didn’t win the U.S. Open.”

Nishikori, who became the highest-ranked male player from Asia when he got to No. 4 in the wake of his run to the U.S. Open final in 2014, lost the 2017 Brisbane final to Dimitrov. That is so far a one-off, with Nishikori now extending his career record to 5-1 against the Bulgarian.

“I’m trying to go (back into) top five, that’s my next goal,” Nishikori said. “I was playing great tennis (last year) and I think I’m doing it again now this week.”

He will next play Jeremy Chardy, who beat Japanese qualifier Yasutaka Uchiyama 6-4, 3-6, 7-6 (4) to reach the semifinals.

Jo-Wilfried Tsonga got an easier path to the quarterfinals than expected, avoiding a second-round contest with 17-time Grand Slam champion Rafael Nadal, who withdrew from the tournament with a thigh muscle strain on Wednesday.

Tsonga then beat Taro Daniel 7-6 (5), 6-3. The 77th-ranked Daniel was the lucky loser from qualifying who got a spot in the main draw when Nadal pulled out.

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