Japan celebrates Osaka's triumph

Japan celebrated Naomi Osaka's victory over Serena Williams in the US Open final, with fans putting her stunning success down to a steely focus and humble attitude as much as her powerful performance at Flushing Meadows.

Osaka was a picture of calm in the midst of her opponent's meltdown that cast a pall over the final.

The 20-year-old, who was born in Japan but raised in the United States, beat her childhood idol 6-2 6-4 on Saturday in a final marred by Serena's multiple outbursts.

"Osaka played so well that Serena wasn't able to play her tennis and she (Williams) got upset," said Mitsuko Sakai, 63-year-old amateur tennis player who woke up at 5 am on Sunday in Tokyo to watch the final.

"She remained so calm throughout the match despite the brouhaha," Sakai said. "I was very impressed by her mental strength. The entire audience seemed to be cheering for Serena but Osaka concentrated on the game and won."

Prime Minister Shinzo Abe congratulated Osaka on Twitter and thanked her for "giving Japan a boost of inspiration at this time of hardship" -- a likely reference to the earthquake that hit the northern island of Hokkaido on Thursday, killing at least 21 people.

Kei Nishikori, who lost in the men's semifinals to Novak Djokovic and was runner-up in 2014, posted a video of Osaka lifting the US Open trophy on his Twitter page along with the hashtag #proud and a Japanese flag.

Japan has been charmed by Osaka's off-court humility and genuineness as much as her on-court ferocity and that unpretentiousness came through in her post-match comments.

While standing on the podium waiting to be handed her trophy, Osaka heard only boos as an angry crowd took out their frustration on umpire Carols Ramos, whom they perceived to have been too harsh on Serena.

"I know everyone was cheering for her and I’m sorry it had to end like this," said Osaka. "I just want to say thank you for watching the match."

Osaka said it was "always my dream to play Serena in the US Open finals," and that, "I’m really grateful I was able to play with you."

Tennis is nowhere near as popular as baseball, football or sumo in Japan, and the match was broadcast live only on the Wowow cable channel, not on any major television channel.

Osaka, the daughter of a Haitian father and Japanese mother, is also helping break new ground in Japan as her biracial identity challenges the country's self-image as a racially homogenous society.

Osaka left Japan when she was three and was raised in New York and Florida. She holds both Japanese and American citizenship and addresses fans on camera in broken Japanese -- which has helped win over the public here.