Naomi Osaka has no regrets over her stunning third-round loss Thursday at the ATP and WTA Cincinnati Masters to Swiss wild card Jil Teichmann.

The four-time Grand Slam champion went down 3-6, 6-3, 6-3 to the world number 76 and admitted after the upset that her Tokyo Olympic third-round loss was on her mind.

“I was doing all I was supposed to do,” the Japanese world number two said. “In the second and third sets I was too defensive. I learned a lot from this match – I can sleep at night.”

Osaka lost to an opponent who has struggled with several injuries this season but is now back to health.

“I knew inside I had this level and I was able to show it on court,” said Cincinnati quarter-finalist Teichmann. “This week things are working out. I needed to be patient and here I am.”

Osaka stayed low-key throughout the post-match media sessions she says she dreads, answering questions and seeming to meekly accept the loss in her final tuneup for the US Open, which begins August 30.

“I have high expectations of myself but there was nothing more I could do to win this match,” Osaka said. “I’m almost glad I lost as it gives me so many things to work on in my game. I just hope the results come in time for the US Open.”

Osaka wished she could have won more than $24,200 in prize money to donate in aid of the earthquake recovery effort in Haiti, her father’s homeland, but tournament officials said they would match her donation.

“I’m happy, but sad that I didn’t go further,” Osaka said. “But I think I raised awareness. I’m glad we were able to contribute something.”

Teichmann took just over two hours to defeat Osaka, breaking the Japanese star six times, three in the final set.

“I felt a bit hesitant, and normally I don’t feel that way,” Osaka said. “I put myself in this position by choosing not to play that many tournaments.”

Osaka has had a rough ride since withdrawing during Roland Garros over emotional issues and skipping Wimbledon. She has played only two hardcourt preparation matches since the Olympics.

“I’m feeling more confident in myself,” Osaka said. “There were times where I was doubting myself. It’s important to remind myself what my strengths are. I think I did that well in the first set.

“In the second set, maybe I played a bit more to her rhythm, and also in the third set, as well.”

Osaka made 41 unforced errors in the match while hitting only 17 winners while Teichmann struck 21 winners against 29 unforced errors.

“I’m happy with how I played today,” Osaka said. “I didn’t give up on any ball. But my point construction could be a lot better.”

Women’s top seed Ashleigh Barty of Australia powered into the quarter-finals 6-0, 6-2 over Victoria Azarenka.

Barty improved to 13-1 over top-20 opponents this season and will next face off against fellow French Open champion Barbora Krejcikova, who beat Garbine Muguruza 6-1, 6-7 (5/7), 6-2

Results

3rd rd

Ashleigh Barty (AUS x1) bt Victoria Azarenka (BLR x14) 6-0, 6-2

Barbora Krejcíková (CZE x9) bt Garbiñe Muguruza (ESP x8) 6-1, 6-7 (5/7), 6-2

Angelique Kerber (GER) bt Jelena Ostapenko (LAT) 4-6, 6-2, 7-5

Petra Kvitova (CZE x11) bt Ons Jabeur (TUN) 6-1, 6-2

Karolína Plíšková (CZE x5) bt Jessica Pegula (USA) 6-4, 7-6 (7/5)

Paula Badosa (ESP) bt Elena Rybakina (KAZ) 6-2, 7-6 (7/5)

Belinda Bencic (SUI x10) bt Karolína Muchová (CZE) 7-5, 2-1, retired

Jil Teichmann (SUI) bt Naomi Osaka (JPN x2) 3-6, 6-3, 6-3