NEW YORK, NY, USA - Naomi Osaka became Japan's first major singles champion on Saturday, shocking former World No.1 Serena Williams, 6-2, 6-4, as the 23-time Grand Slam champion was aiming to tie Margaret Court's all-time record at the US Open.

"It doesn't really feel that real right now," Osaka admitted in her post-match press conference. "I think maybe in a few days I'll realize what I've done. Right now it just feels, like, I don't know. Aside from the fact there's a lot of press in this room, it feels just like another tournament."

Playing her first Grand Slam final, the 20-year-old No.20 seed beat idol Serena for the second time in 2018, backing up her Miami Open stunner with a 79 minute victory on Arthur Ashe Stadium.

Williams was not only going for history, but was also trying to become the first mom to win the US Open since Kim Clijsters in 2010 - and the first at any major tournament since Clijsters won the Australian Open in 2011. Starting out with a confident hold of serve, Williams lost five straight games to start the match as Osaka settled in with strong serves and grounstrokes.

The Japanese youngster served out the opening set, but the match was far from over as Serena snapped Osaka's streak of saving 22 straight break points in her last three matches came to an end after a long fourth game in the second set.

Serving for a 4-1 lead, Williams threw in two uncharacteristic double faults as Osaka broke back. Williams incurred a point penalty after receiving a coaching violation and breaking a racquet. 

"I felt like I shouldn't let myself be overcome by nerves or anything, and I should just really focus on playing tennis because that's what's gotten me to this point. So, yeah, I just thought, like, no matter what happens outside of the court, for me, when I step on the court, it's just about tennis."

Osaka gamely held on and struck a searing passing shot to get within two games of victory.

Engaging with umpire Carlos Ramos after the point penalty, Ramos issued Williams a code violation for verbal abuse, which triggered an automatic game penalty to put Osaka up 5-3.

"I don't know how I'm feeling yet," Serena said after the match. "Haven't had time to really process everything. But I'm just trying to stay positive and to,look at all the bright things and all the good things and just keep going forward with that."

Putting down a defiant service hold, the American couldn't hold off the No.20 seed, who served out an emotional victory over the woman who inspired her to play tennis.

"I felt at one point bad because I'm crying and she's crying," Serena said. "You know, she just won. I'm not sure if they were happy tears or they were just sad tears because of the moment. I felt like, 'Wow, this isn't how I felt when I won my first Grand Slam. I definitely don't want her to feel like that.' Maybe it was the mom in me that was like, 'Listen, we got to pull ourselves together here.'"

In all, Osaka struck 15 winners to 14 unforced errors and converted an impressive four of five break point opportunities.

The win will also take her to a new career-high ranking and a Top 10 debut, the first Japanese woman to crack that threshold since Ai Sugiyama in 2004.

"I'm going to Tokyo next, so hopefully to win the tournament there," Osaka said when asked about her next dream. "I'm just going to take it one step at a time. I'm not going to really think too far ahead."