Naomi Osaka made history on Thursday, becoming the first Japanese woman to reach a Grand Slam final by beating American Madison Keys in straight sets at the U.S. Open.

The 6-2, 6-4 semifinal win sets up a final against Osaka's childhood hero Serena Williams, the 23-time major winner earlier cruising into her ninth U.S. Open final.

"(The win) means a lot, especially since everyone in my team is watching, thank you guys," said the world No. 19 from Japan.

When questioned about what drove her to play such high-level tennis, she said it was just one thing: "Serena."

"This is going to sound really bad, but I was just thinking that I really want to play Serena...because she is Serena," she said on the court after her win.

"It still feels really weird because I have never beaten Madison before, but I was just really glad that I could get through this match."

Two other Japanese women have reached a Grand Slam singles semifinal, Kazuko Sawamatsu at the Australian Open in 1973 and Kimiko Date, who did it three times between 1994 and 1996, but none can match the achievement of the 20-year-old Osaka-born player.

It took just five games for Osaka to get on top. After fending off three break points in her second service game, the 20-seeded Japanese quickly broke Keys to claim a 3-2 lead.

Osaka then held to give herself a 5-2, double-break buffer, a lead she would not give up as she wrapped the set up in 37 minutes.

Keys had her opportunities in the first, six break points in total, but she was unable to capitalize, unlike the Japanese who won two of her three chances to break.

Osaka maintained the momentum at the start of the second, immediately breaking Keys, but then the American ramped up the pressure.

The 14th seed forced six break points on Osaka's first service game of the second, but the Japanese was equal to the task -- saving two with aces, one on a second serve -- to take a 2-0 lead.

Now settled, Keys remained solid on serve throughout the rest of the set, but, crucially, so did Osaka as she closed it out 6-4.

Earlier on Thursday, Williams reached her 31st career Grand Slam final with a 6-3, 6-0 win over Anastasija Sevastova.

The current world No. 26 Williams proved too powerful and poised for the Latvian who was playing in her first Grand Slam semifinal, the all-time great cruising through with five service breaks to her opponent's one.

Incredibly, Osaka holds a career head-to-head advantage over Williams. In their one previous meeting, at the 2018 WTA tournament in Miami, Osaka ran out a 6-3, 6-2 first-round winner.

But when asked what message she has for her U.S. Open final foe, Osaka could not muster any fighting talk, simply saying she wanted Williams to know that "I love you."