How Naomi Osaka Lost

But the potential for a storybook ending fizzled over 68 minutes Tuesday afternoon, when, for long stretches early in the match, Osaka battled to keep the ball in play. She committed 20 errors in the set, 14 of them unforced, and could not rely on her serve to take control of the match the way she usually does.

The loss stunned the handful of people in attendance at Ariake Tennis Park, where a phalanx of Japanese photographers lined the court. Osaka was a favorite to win the tournament on home soil, especially after Ashleigh Barty, the No. 1, was eliminated in the first round, and when other top players lost in Round 2.

Osaka was also seeking a moment of redemption after she dropped out of the French Open over a dispute with tournament officials over whether she should have to attend mandatory news conferences after her matches. After the loss on Tuesday, she made a brief visit to the players’ lounge after the match, then left the grounds, before returning later to speak briefly with the news media.

“I’m glad I did not lose in the first round, at least,” she said.

Because Osaka lit the Olympic cauldron late Friday night in the climax of the opening ceremony, her opening match was moved from Saturday morning to Sunday. As a result, Osaka was playing for a third consecutive day.

She battled to find her rhythm in the second set, which was much tighter than the first, but Vondrousova played with a cool beyond her 22 years, neutralizing Osaka’s power with a series of spins and slices that never allowed Osaka to get comfortable.

“Naomi is the greatest now,” Vondrousova said after one of the biggest wins of her career. “She was also the face of the Olympics, so it was also tough for her to play like this.”

When it was over, in a brief exchange at the net, Osaka told her “good match” and Vondrousova thanked her for the compliment.