Serena Williams puts an arm around Naomi Osaka at the trophy ceremony.
Serena Williams puts an arm around Naomi Osaka at the trophy ceremony.

‘I felt like I had to apologise’

NAOMI Osaka has spoken about the mixed emotions she felt after beating her childhood idol Serena Williams in a US Open final marred by controversy.

Two days after winning her first Grand Slam title, the 20-year-old said she was "really emotional" up on the podium standing beside Williams, admitting she felt like she had to apologise to fans of the former world No 1.

"I felt a little bit sad because I wasn't really sure if (the crowd) were booing at me or if it wasn't the outcome that they wanted," Osaka said during an interview on NBC's Today show.

"I also could sympathise because I've been a fan of Serena my whole life. And I knew how badly the crowd wanted her to win, I don't know, I was just really emotional up there."

Osaka's win in straight sets at Arthur Ashe Stadium in Queens on Saturday was overshadowed by boos when Williams was slapped with a violation by chair umpire Carlos Ramos during the second set.

Osaka, who has lived in America most of her life but represents the country of her birth, Japan, said she wasn't aware of what was happening while her opponent argued with the umpire - eventuating in her being penalised a point, and then an entire game after she called him a "thief".

"I just felt like everyone was sort of unhappy out there and I knew it wasn't the ending that everyone wanted it to be. In my dreams I won in a very tough, competitive match, so I just felt very emotional and that I had to apologise," Osaka said.

She said she was overwhelmed when her long-time tennis idol congratulated her during the post-match interview.

"I felt really happy because I sort of felt that she knew I was crying … It just made me happy overall."