Naomi Osaka lost to former French Open finalist Marketa Vondrousova of the Czech Republic 6-1, 6-4 in the third round of the Tokyo tennis tournament on Tuesday.
The second-ranked Osaka, who was born in Japan and grew up in the United States, struggled with her usually reliable groundstrokes.
The 42nd-ranked Vondrousova produced a series of drop-shot winners and other crafty shots that drew Osaka out of her comfort zone.
The 23-year-old had hoped to play a starring role in the Games on the court as well as off it but lighting the Olympic flame at the opening ceremony will be the high point.
Osaka had looked good in her first two matches, particularly against Viktorija Golubic on Monday, but former French Open finalist Vondrousova was a step up in level and the young Czech produced an excellent performance under the roof at the Ariake Tennis Park.
Osaka admitted the occasion had played its part, saying: “I feel like I should be used to it by now. But, at the same time, the scale of everything has been a bit hard because of the break that I took. I am glad I didn’t lose in the first round at least.
“I am really glad to be here. I am sad I lost, of course, but all in all, I am really happy with my first Olympic experience.”