Naomi Osaka, the Japanese superstar who lit the cauldron during the Olympic opening ceremony, was eliminated in the third round of the women’s singles tennis tournament on Tuesday in straight sets.

Osaka lost, 6-1, 6-4, to Marketa Vondrousova of the Czech Republic in barely over an hour in a stunning upset of the host country’s biggest sports celebrity.

Osaka — a favourite to win the tournament on home soil — breezed through her first two matches, the first competition she has faced since dropping out of the French Open. But on Tuesday, she struggled from the outset, committing 20 errors in the first set, 14 of them unforced.

The loss stunned the handful of people in attendance at Ariake Tennis Centre, where a phalanx of Japanese photographers lined the court.

Osaka said the pressure of being the face of the event probably played a role in the loss but did not want to use it as an excuse.