MIAMI GARDENS, Fla. — A little more than two years ago, over dinner during the Australian Open, Iga Swiatek told Naomi Osaka that she wasn’t sure a career in tennis was going to go her way, so she was thinking of going to college.

Osaka, who was 22 then and had already won two Grand Slam titles, told Swiatek that was a terrible idea. You’re really good, Osaka told Swiatek, who at the time was still cramming in high school homework. Don’t divert your energy to college just yet, Osaka advised.

Swiatek took Osaka’s advice, and good thing she did. Nine months later she came out of nowhere to win the French Open while she was ranked 54th in the world. Saturday, in a clash of styles, narratives and friends in the finals of the Miami Open, Swiatek ended a run that Osaka hopes will mark the beginning of the next chapter of her turbulent career with a 6-4, 6-0 win to cement her remarkable rise to the top of her sport.

Next week, Swiatek will officially take over the No. 1 ranking, the first player from Poland to rise to that lofty perch. As she held the winner’s trophy, Swiatek called Osaka “an inspiration” and said she would never have imagined when they were having that dinner that they might actually be playing each other for championships one day.

“I think it’s the start of a great rivalry,” Swiatek said.

For Osaka, this tournament marked a remarkable turnaround that few saw coming, even if she felt like it was not far off. Just three weeks ago at the BNP Paribas Open in Indian Wells, a lone heckler rattled her during her second round match, bringing her to tears and triggering memories of the racist treatment Serena and Venus Williams endured at the event two decades ago.

But it also seemed to suggest that Osaka, who lost 6-0, 6-4 to Veronika Kudermatova that night, might not be up for the grind and pressures of the professional tennis tour after a year filled with breaks and setbacks, a disclosure of a yearslong struggle with her mental health and questions about whether playing tennis could ever make her happy.

In South Florida though, her home for most of her childhood, a far-steelier Osaka took the court, and she played a lot like she had when she won four Grand Slam tournaments. She won eight consecutive sets on the way to a semifinal match in which she battled back against an opponent, Belinda Bencic of Switzerland, who had beaten her repeatedly for years.

Osaka was once more ripping forehands through the court and coming up with unreturnable laser serves when she needed them most. Beyond the tennis, though, there has been a lightness to her experience. Even in defeat Saturday, she could not help but grin as the hometown crowd smothered her with cheers.

They were never louder than when James Blake, the former pro and the tournament director for this event, gazed at Osaka during the awards presentation and said, “I can’t tell you how good it makes me feel to see you happy again.”

Then it was Osaka’s turn. “I know I haven’t been in this position for a little while,” she told the crowd after her first final since the 2021 Australian Open. “The outcome wasn’t what you wanted, but hopefully I can keep working hard and be in a position to do this again soon.”

In the past, she would say later, she would be crying with disappointment following a day like Saturday. Instead, she experienced it as “a sad outcome but a fun day.

“It’s cool to see where the level of No. 1 is and to see if I can reach that,” she said.

In Swiatek, Osaka ran into a version of a player that didn’t exist when Osaka was last a mainstay of important tournaments.

With the sudden retirement of Ashleigh Barty last week, Swiatek earned the No. 1 ranking, owing largely to a white-hot start to the year. Since her loss in the semifinal of the Australian Open, Swiatek has won three masters-level titles, in Doha, Indian Wells, and Miami, events that are just below the Grand Slams.

Saturday’s final riding a 16-match winning streak. But it is the manner in which she has managed all the winning that has her opponents leaving the court with a dazed and glazed look in their eyes.

Gone is the shaky mind that used to rattle after a handful of lost points or games or a set. She has evolved into a ruthless problem solver who tears through opponents, especially in finals. She has seemingly gained a half-step — or maybe just a willingness to embrace the next level of fatigue — that allows her to extend points and force opponents to hit extra shots when they thought the point was over.

She also is just about the only player in the world who can consistently pull off a kind of tennis magic trick when a ball comes rocketing across the net and lands inches from her feet. In a split second, Swiatek squats so low that her skirt is basically on the ground and fires a kind of swinging half-volley that allows her to go back on the attack. She seems to invent a new shot in every match these days. Saturday it was a back-spinning squash shot lob that landed within inches of the baseline.

Osaka, who entered the tournament ranked 77th, had little to lose in the final. She had never lost the final of either a Grand Slam or a Masters 1000 tournament, but neither had Swiatek. Osaka positioned herself several steps into the court on Swiatek’s second serve, trying to rely on her quick hands and instinctive skill to punch the ball back and keep Swiatek off balance.

The strategy never quite clicked. “I could never really figure out what to do,” Osaka said.

Swiatek never faced a break point, and she had Osaka on the defensive from the start. It took Osaka 11 minutes to hold her serve in the first game. On the afternoon, she won nearly two-thirds of the points on her first serve, which hovered in the neighborhood of 120 m.p.h., but just one-third of those on her second, which was often in the mid-70s.

Osaka’s next move will be closely watched. The clay court season in Europe is fast approaching. Clay has long been her worst surface. Grass is no picnic for her either. But she said she will travel to Europe later this month to prepare for the Madrid Open, and has an extra week of preparation built into her schedule.

After months of questioning what she wanted from her tennis life, she desperately wants to do well, she said. She wants to be seeded for the French Open, which would likely mean being around the top 30. And she wants to be in the top 10 by the end of the year and reclaim the top ranking next year.

“It feels kind of good to chase something,” she said. “That is a feeling I have been missing.”