Defending champion Naomi Osaka's hopes for a third Grand Slam singles title were dashed Monday after she was knocked out of the U.S. Open by Belinda Bencic of Switzerland.

Top seed and world No. 1 Osaka suffered a 7-5, 6-4 loss at the hands of the 13th-seeded Bencic in their round of 16 clash at Arthur Ashe Stadium.

But the 21-year-old Japanese held her head high at the post-match press conference, saying she is neither disappointed nor angry because she played well through the summer and the U.S. Open, the final Grand Slam of the year, has been her best tournament so far.

"Right now, I have this feeling of sadness, but I also feel like I've learned so much during this tournament," Osaka said.

"In Wimbledon, I walked out on you guys (the media). In Roland Garros, I came straight from the match so I was all gross and I just wanted to get out of there. As you can see, I took a shower (today). I feel like I'm more chill now. I feel like I grew. I don't feel like I put so much weight on one single match."

Osaka got off to a shaky start, dropping serve in the opening game with a double fault on Bencic's first break chance.

But after successfully defending four break points in the third game, Osaka got on the board and went on to level the set at 2-2. She appeared to have steadied herself, unleashing six aces in the set and nine in the match as compared to none by her opponent.

It was a brilliant sequence by Bencic late in the set that eventually gave her the advantage. After earning a break point at 30-40, Bencic played a short return that drew Osaka to the net, then blasted a backhand winner past her for the game.

She held serve despite two double faults in the following game to win the hard-fought set.

Osaka did not see a single break opportunity in the second set, and her mistakes in the fifth game were costly. Already down 0-30 in that service game, Osaka failed to put away an easy point at the net -- her backhand volley was fired right back by Bencic for a winner to set up a triple break chance.

Osaka then committed her second game-ending double fault of the match, handing her opponent the decisive break. Five games later, Bencic finished off the defending champion with a love hold to take the match in 1 hour, 26 minutes.

The 22-year-old Swiss will face Donna Vekic of Croatia in a quarterfinal round featuring No. 5 seed Elina Svitolina and No. 8 seed Serena Williams, but missing No. 2 Ashleigh Barty and No. 3 Karolina Pliskova after they too were eliminated at the round of 16.

With the loss, Osaka will slip back in next week's official WTA rankings, ceding the top spot to Australia's Barty, who was No. 1 for a period of eight weeks earlier this summer.

Before Monday, Osaka had lost two matches against the 12th-ranked Bencic this season, once at Indian Wells in her first title defense and most recently in the Madrid Open quarterfinals.

Last month, Osaka was forced to retire from her quarterfinal at the Western and Southern Open in Cincinnati because of a left knee injury.

"I hurt my knee in Cincinnati but it's getting better. I don't want to say that's the reason I lost because, obviously, I played three matches before this. I just needed to take a painkiller," Osaka said.

"The knee was a little bit annoying in the movement aspect, but that's something that I should have overcome."

Osaka has not reached the final of a tournament since winning her second straight Grand Slam at the Australian Open, but entered Monday's match having dropped only one set in the tournament.

At last year's U.S. Open, Osaka defeated her childhood idol Serena Williams in the final to become the first Japan-born player to win a Grand Slam.

Osaka will next play at the Sept. 16-22 Toray Pan Pacific Open in Japan. "To be honest I'm not even thinking about playing tennis there (in Osaka) right now. All I'm thinking about is the takoyaki. I'm just there for the food," she joked.


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