MIAMI GARDENS, Fla.— Thirteen months.

That’s how long it’s been since Naomi Osaka played for a championship in a big-time tennis tournament, and a few weeks ago it looked like it might be 13 more.

But during the last nine days, Osaka, who once appeared on the verge of piling up tournament titles the way children collect stuffed animals before divulging struggles with her mental health, has burst out of the tennis wilderness. Her timing, following the sudden retirement last week of Ashleigh Barty, the world No. 1, at 25 years old, could not have been better.

Right on cue, the half-Haitian, half-Japanese Osaka, who was raised in the United States and is the biggest star in the women’s game with Serena Williams inactive, has once more become a force. Thursday’s three-set semifinal win over Belinda Bencic of Switzerland at the Miami Open served as her return to the top of women’s tennis, at one of the sport’s most important events outside of the Grand Slams.

How long Osaka will stay on the favorable side of the tennis ledger and in good spirits is anyone’s guess, as she would be the first to admit. She has flirted with optimism before, only to fall victim to the stress and strain of life as a professional tennis player and as one of the world’s most recognizable, highly compensated and outspoken athletes.

But for a little over a week — at least within the confines of the tennis courts at Hard Rock Stadium in South Florida, the region where she first wowed the tennis cognoscenti in her early teens — Osaka has come around again.

Before Thursday, when she survived a three-set battle with Bencic, 4-6, 6-3, 6-4, she had not dropped a set in five matches in Miami, including a third-round walkover. But Osaka has hardly been perfect; she even lost her serve on her first chance to close out Bencic. But she is once more pushing opponents around the court, pounding serves to the corners, smacking frozen-rope forehands mere inches above the net, scaring the lines, and using her nearly unmatched speed to chase down deep balls in the corners. She is showing a willingness to suffer and do the hard things.

She will face Poland’s Iga Swiatek, the new world No. 1, in the final on Saturday.

“I’d be lying if I said I didn’t want to be No. 1 again,” Osaka said in a television interview after she made her first final at any tournament, large or small, since the 2021 Australian Open.

That may not sound like so long ago, but Osaka has lived a saga since then, falling from No. 2 in the world rankings and her perch as the reigning champion of two Grand Slams to No. 77. There have been so many twists and turns and breaks and restarts that it can be hard to believe that less than a year has passed since Osaka’s tennis life began its public descent. Her inner turmoil had been brewing much longer, but she had learned to disguise it.

“If I didn’t say anything at the French, I don’t think anyone would have known about the things that I’m going through,” she said on Thursday.

At the French Open last May, Osaka announced that she would not participate in the mandatory post-match news conferences because they were too taxing on her psyche. The policy, she wrote on social media, showed how little regard tennis officials had for the mental health of players. Though nearly all of her fellow stars said they empathized with Osaka, they accepted that speaking with the press was part of the job.

After tournament officials threatened to expel her from the tournament, she withdrew following her first-round match and did not play again until the Tokyo Olympics, where she lit the torch but came apart in the third round amid relentless pressure.

Her third-round loss to Leylah Fernandez at the U.S. Open, where she was a favorite to successfully defend her title, led to a tearful admission that playing tennis no longer made her happy, and that when she won, she felt relief rather than joy.

Four months passed before Osaka played again. At the Australian Open in January, she showed occasional flashes of the player who won four Grand Slam singles titles before her 24th birthday, but she fell in the third round to Amanda Anisimova in three hard-fought sets, 4-6, 6-3, 7-6 (10-5).

At the time, she expressed satisfaction with how hard she had fought, saying she felt like she had won some games through “sheer willpower.” Then she did not play another match for six weeks, until the BNP Paribas Open at Indian Wells.

There, a lone heckler rattled her during her second round match, bringing her to tears during a one-sided loss to Veronika Kudermetova. She said the heckler triggered memories of the racist treatment Serena and Venus Williams endured at the event two decades ago.

Osaka asked for the chair umpire’s microphone to speak to the crowd in the middle of the match. Tournament officials turned her down. Once again, her fellow players mostly expressed empathy, then spoke of dealing with jerks in the stands as an unfortunate hazard of their occupation. Given her recent past, no one knew when the woman who walked through stadium hallways wearing Beats headphones and listening to a playlist she called “Sad” might play again.

She did. She spoke with a therapist and embarked on yet another reset, and she now can’t quite believe how quickly it has come. Even if Osaka said she was shaking as she served during her match against Bencic, who had won four of their five previous meetings, in Miami, there have been few signs of the fragility of Indian Wells.

Quite the opposite. Here, a dismissive comment Osaka heard on television from the former world No. 1 Caroline Wozniacki served as motivation. Ahead of Osaka’s second-round match against Angelique Kerber of Germany, she heard Wozniacki say she was expecting a third-round matchup between Kerber and Fernandez, and that voice was in her head as she took on Kerber.

“I was like, ‘Hmm, I know I was kind of underachieving these last couple of months, but I still feel like I’m a pretty good player,’” Osaka said after dominating the 13th-seeded Kerber, 6-2, 6-3. (Wozniacki, who retired in 2020, may be better at tennis than prognosticating. Fernandez also lost her second-round match.)

Down a set to Bencic on Thursday, she told herself she might lose, but that if she did, she would leave the court on a stretcher. The stretcher wasn’t necessary — not after she served 18 aces .

When it was over, Osaka sat in her chair and buried her face in a towel — but not in relief.

“It was definitely happiness,” she said. Soon, she was trying to figure out if she could order Korean beef ribs for dinner, a break from all the Haitian food she had been eating in her old stamping ground.

There were tears, which she wiped away as she thanked the crowd, but they were an altogether different kind. “Damn, I’m always crying,” she said. “It’s been awhile since I’ve been in the finals.”