Naomi Osaka is about her business at US Open

NEW YORK — Defeat the defending champion in the opening round of a Grand Slam, and you’re allowed a moment. So Naomi Osaka of Japan would have gotten a pass had she tossed her racket, dropped to her knees or even moonwalked after her opening-round win over No. 6 seed Angelique Kerber in the US Open.

Watching Kerber hit a return into the net to end the match, the unseeded Osaka did none of the above. Void of any type of emotion, the 19-year-old Osaka walked calmly to the net after taking just over an hour to easily defeat Kerber, 6-3, 6-1, in front of an appreciative crowd at Arthur Ashe Stadium.

“I felt relieved, especially since I was nervous on the last point,” said Osaka, who lives and trains in Florida with her Haitian father. “I was rarely happy because I grew up watching the greatest players play on that court, so to win a match on it felt really special.”

Osaka’s win was the start of an impressive day for players of color under the roof of the main court on a day where most of the matches were washed out.

Madison Keys, seeded 15th, opened the night session with a straight-sets win over Elise Mertens of Belgium, 6-3, 7-6 (6). And in the last match of the day, 19-year-old Frances Tiafoe, whose parents are immigrants from Sierra Leone, put a scare in Roger Federer before losing to the No. 3 seed in an epic five sets (4-6, 6-2, 6-1, 1-6, 6-4).

Tuesday’s shocking win by Osaka proved for the second straight day that the women’s singles division of the US Open, in the absence of the pregnant Serena Williams, is wide-open. Osaka’s first win over a top-10 opponent (Kerber is also ranked No. 6 in the world) came a day after second-seeded Simona Halep lost to unseeded Maria Sharapova, a career Grand Slam winner playing her first major since returning from a suspension for a failed drug test at the 2016 Australian Open.

Perhaps the subdued reaction of Osaka, No. 45 in the world, was due to the memories she had from the last time she played at Arthur Ashe Stadium in the third round of last year’s US Open, when she lost to No. 8 seed Keys. Up 5-1 in the final set, Osaka dropped the next five games before eventually losing the third-set tiebreaker in a collapse that was painful to watch.

“The experience last year helped me this year,” Osaka said. “I felt the same type of nerves come up when I was up, 4-1, in this match. I told myself to just keep playing how I was playing and not let the nerves get over me as much as last year.”

She may have felt nerves on the inside, but they were kept hidden from her opponent and the fans. Osaka had the court well-covered with her agility and kept Kerber on the defensive the entire match. Kerber, who hasn’t played well this year, had five double faults (Osaka had none) and 23 unforced errors.

“She’s very aggressive,” Kerber said. “She served well, and she was going for it. I think she took the chances and she played a very good match.”

There were questions about Osaka’s health entering the US Open. In her previous match at the Rogers Cup last month in Toronto, Osaka retired with abdominal pain while down 1-0 in the third set of a winnable contest against world No. 1 Karolina Pliskova.

“Having to withdraw really hurt my feelings, especially since I was playing the No. 1 and I felt like I was doing really well,” Osaka said. “I went home and trained for two weeks, and I did a lot of fitness.”

Born in Japan, Osaka is a citizen of both the United States and Japan. She represents Japan (as does her older sister, Mari Osaka) despite the fact that she’s lived in the United States since she was 3 years old, even spending part of her childhood on Long Island, New York, not far from the USTA Billie Jean King National Tennis Center in Queens.

“When we were little, we would come to the US Open every year,” Osaka said. “We would practice, and sometimes I would play here, so the site feels really familiar to me. It’s like nostalgic every time I come here.”

As Osaka and her older sister played as kids, they were often asked whether they were destined to be the next Williams sisters. Osaka, who idolizes Serena Williams, said she was nervous when she faced Venus Williams in the third round of Wimbledon this year, losing in a hard-fought match (7-6, 6-4).

Osaka said playing against Williams at Wimbledon helped her against Kerber.

“I told myself that the last Grand Slam I played Venus and I have huge respect for Venus and Serena,” Osaka said. “I tried to tell myself I’m probably not going to get as nervous against Kerber.”

Osaka used to get really nervous answering questions from the Japanese media. When the moderator of a postmatch news conference turned it over to the Japanese media last year, Osaka, who is not fluent in Japanese, begged off.

“She said, ‘No, no, we can’t do that,’ ” said Akatsuki Uchida, a reporter with the Japanese news organization Smash. “It was quite tough when she first came on tour because she was shy and she was reluctant to speak Japanese.”

That changed in last year’s French Open, and on Tuesday Osaka took questions in Japanese (while answering in English).

“She said, ‘I’m going to try a Japanese press conference,’ and now she does it often,” Uchida said. “She really loves Japan, and the Japanese people are starting to learn the type of personality that she is.”

Despite her mixed racial heritage, Uchida said, Osaka is fully embraced in Japan.

“We’re an isolated island, but we have a lot of mixed Japanese athletes in track, baseball and other sports,” Uchida said. “We are getting more diverse.”

Osaka is beginning to get more comfortable as she represents the bright future of women’s tennis. When Serena Williams was asked about Osaka during the 2016 Australian Open, she said, “She’s really young and very aggressive … very dangerous.”

And now extremely confident.

“Moving forward,” Osaka said, “I feel like I know that I can play with the top players.”