Naomi Osaka of Japan holds up the championship trophy after defeating Serena Williams of the US in the women's final on the thirteenth day of the US Open. Photo: Justin Lane/EPA
Naomi Osaka of Japan holds up the championship trophy after defeating Serena Williams of the US in the women's final on the thirteenth day of the US Open. Photo: Justin Lane/EPA
Naomi Osaka of Japan is embraced by her coach Sascha Bajin after defeating Serena Williams. Photo: Daniel Murphy/EPA
Naomi Osaka of Japan is embraced by her coach Sascha Bajin after defeating Serena Williams. Photo: Daniel Murphy/EPA

NEW YORK – Naomi Osaka became the first Japanese woman to win a Grand Slam title on Saturday as her idol Serena Williams angrily imploded, calling the chair umpire in the US Open final "a thief".

Osaka, 20, triumphed 6-2, 6-4 in the match marred by Williams's second set outburst, the American enraged by umpire Carlos Ramos's warning for receiving coaching from her box.

She tearfully accused him of being a "thief" and angrily demanded an apology from the official.

When a second code violation for racquet abuse was handed out to her - along with a point penalty - Williams exploded.

"You're attacking my character," she said. "You will never, ever be on another court of mine. You are the liar," she fumed and Ramos handed her a game penalty that put Osaka one game from victory at 5-3 in the second set.

Williams won the next game, and continued her tearful remonstrations with a supervisor on the change-over but Osaka - who displayed remarkable poise throughout - held serve to seal a historic win for her country.

Agence France-Presse (AFP)