Naomi Osaka is through to her first tournament final since her 2021 Australian Open win, getting past Belinda Bencic 6-4 3-6 6-4 at the Miami Open on Thursday.

The reigning Olympic champion looked strong early, breaking twice to go up 4-1 as she took advantage of Osaka's second serve, winning nine of the 11 second serves she saw in the opening set.

As Osaka's success on second serve cleaned up in the second set, Bencic's avenue to victory vanished, unable to save either of the two break points she faced in the second set.

Osaka's first serve percentage shot up to 70 in the deciding set, winning 87 per cent of points on first serve (20-23) to shut the door. Despite Bencic breaking back once after going down a double-break, she was unable to stop her Japanese opponent from serving it out.

Speaking on court after her win, the Florida native was emotional, shedding some tears as she thanked the fans in attendance.

"I just wanted to say thank you everyone, the atmosphere was really good," she said.

"Damn, I'm always crying. I just wanted to say thank you, this tournament really means a lot to me and it's my first time in the finals here."

World number-one-in-waiting Iga Swiatek twice came back from a break down in the second set to overcome the challenge of American Jessica Pegula 6-2 7-5.

The straight sets win for the 20-year-old Polish star means she has now not dropped a set in eight straight matches dating back to the fourth round at the Indian Wells Open where she beat Angelique Kerber two sets to one.

Against Pegula, Swiatek was simply too strong in the opening set, breaking twice in four tries when Pegula's second serve was vulnerable, with the American only winning 27 per cent of her second serve points (4-15) in the opening frame.

The second set was far more competitive, but Swiatek remained just slightly better both on serve and in the return game in a set where four consecutive games resulted in breaks in a seesawing contest.

Pegula refused to let the top seed serve it out comfortably, saving two match points to extend the second set at 5-5. It was just delaying the inevitable as Swiatek broke back instantly and held her nerve, and serve, to avoid a tie-break.