If anyone still did not believe Naomi Osaka’s game was all the way back, her gritty performance under the U.S. Open spotlight Wednesday night emphatically quieted any remaining doubters of the former No. 1 player in the world.

Even herself, perhaps, most significantly.

After crushing 2023 Open champion and American fan favorite Coco Gauff in straight sets in the Round of 16, Osaka moved into the semifinals of a Grand Slam tournament for the first time since returning last year from maternity leave and a mental break with a 6-4, 7-6 (3) victory over No. 11 seed Karolina Muchova to kick off the night session at Arthur Ashe Stadium.

Naomi Osaka reacts during her U.S. Open quarterfinal win over Karolina Muchova on Sept. 3, 2025. AP

The victory sets up a clash in the semis Thursday night between the Japan native and eighth-seeded American Amanda Anisimova, who dispatched No. 2 Iga Swiatek on Ashe to conclude the day session. Every time Osaka has reached a semifinal of a Slam event, she has gone on to win the tournament.

“Definitely. I think for me I appreciate the journey a lot more now,” the 27-year-old Osaka said during her postmatch news conference. “I think when I was younger, I kind of just kept thinking the next one, the next one, the next one.

“Obviously I would love to appreciate everything right now, but I have a match to play tomorrow. Yeah, they put the mom on last. That’s crazy.”

Karolina Muchova reacts during her U.S. Open loss to Naomi Osaka on Sept. 3, 2025. Getty Images

Osaka only has dropped one set — to Daria Kasatkina in the third round — among her first five matches during this fortnight in Flushing Meadows.

Playing in her first Grand Slam quarterfinal since winning the Australian Open in 2021, the resurgent Osaka won 65 percent of her first serves, including five aces.

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The 2018 and 2020 U.S. Open title winner was the top-ranked player in the world after capturing four major titles altogether — also including the Aussie Open twice — through 2021 before missing the entire 2023 season to take care of mental issues and to give birth to her daughter, Shai.

“I learned I loved tennis way more than I thought I did, and I learned that, I actually really love challenges,” Osaka said. “It’s like a video game. You pick it up, and even if you lose a level, you kind of just restart and keep going until you eventually win.

“I think it’s been a little tough at times, but I wouldn’t trade it for the world.”

Naomi Osaka hits a forehand against Karolina Muchova on Sept. 3, 2025. REUTERS

Osaka has admitted uncertainty about getting back to this level of play, with two first-round ousters, three second-round departures and two third-round advancements — including at Wimbledon earlier this summer — in her previous seven appearances at the majors since returning to the tour.

But Osaka’s confidence rose — as did her WTA ranking to No. 23 — with a run to the championship round of the Canadian Open in Montreal last month, and she has carried that over to New York under new coach Tomasz Wiktorowski.

Muchova had bounced Osaka, who was playing as a wild-card entry, in straight sets in the second round here one year ago.

Muchova dominated her first four service games, losing only two points, but Osaka also held serve throughout the first nine games of the match. After grabbing a 5-4 lead, Osaka capitalized on three unforced errors by her Czech opponent for her first break points of the night and seized the opening set at 15-40.

Naomi Osaka of Japan returns a volley against Karolina Muchova of Czech Republic. JASON SZENES/ NY POST

After Muchova took a brief medical timeout between sets, Osaka immediately dropped her first service game. But she regrouped quickly and evened matters with her second straight break before grabbing a 2-1 lead with a crisp backhand winner.

Osaka had the throngs roaring with a rush to the net for a forehand passing shot to go up 3-2, but couldn’t hold that momentum as Muchova closed out for her next two service games to get to 4-4.

Osaka overcame one break point with a cross-court forehand but then sent a backhand barely wide to open the door for Muchova to try to serve for the second set.

Naomi Osaka celebrates her U.S. Open win over Karolina Muchova on Sept. 3, 2025. AP

The two-time Open semifinalist squandered that opportunity, however, as Osaka got back on track with another Muchova unforced error on triple-break point for a 5-5 knot.

Osaka erased a break point three times in the following game, and the New York crowd clearly appreciated her perseverance as she screamed “come on” after grabbing a 6-5 lead.

Muchova then made it to the tiebreaker, but Osaka’s baseline game was too strong as the crowd erupted once more when Muchova’s return sailed long on match point.

“Definitely it was a really tough match I think for me. Honestly, I was just trying to hang in there and see if I got an opportunity,” Osaka said. “What I am satisfied with today’s match [is] I think my mentality.

“I think there were a lot of moments where she broke me or she was really close to getting a really crucial moment or point, and I just tried to play every point like it was the last point of the match. Thankfully it worked out.”