TOKYO — A third athlete at the Olympic Village in Tokyo has tested positive for COVID-19, with the Czech Republic team reporting the case Monday of a beach volleyball player who could miss his first game.

The positive case of an American gymnast, who was not identified and is an alternate on the women's team, also was confirmed by the United States Olympic and Paralympic Committee. Olympic champion Simone Biles was not affected by the result, nor were any of the other gold medal favorites on the team.

Czech beach volleyball player Ondřej Perušič could miss his opening game on Monday after a PCR test confirmed his infection. Perušič and his playing partner are due to the begin their Olympic program against a team from Latvia.

Czech team leader Martin Doktor said in a statement they would ask to postpone the game until the infected player is cleared to play.

Perušič, who said he has been vaccinated, is the second member of the Czech delegation to test positive in Tokyo after a team official's case was reported Saturday.

He is the third athlete who was staying at the village to test positive. Two South African men's soccer players had their COVID-19 cases announced Sunday.

The players and a team video analyst who tested positive one day earlier were moved to the “isolation facility” managed by the Tokyo Olympic organizing committee.

Their 21 close contacts around the South Africa team now face extra scrutiny before their first game Thursday against Japan in Tokyo. The monitoring regime includes daily testing, traveling in a dedicated vehicle, training separately from teammates not affected and being confined to their rooms for meals.

“Although you are a close contact, you are able to do the minimum that you need to do so that you can continue your preparation for the Games while you are being monitored,” said Pierre Ducrey, the Olympic Games operations director.

Earlier Monday, before the Czech case was reported, Tokyo Olympic organizers confirmed three new COVID-19 cases, including a media worker arriving in Tokyo and a Games staffer or official in the Chiba prefecture.

Both people, who were not identified, went into a 14-day quarantine, organizers said.

The Tokyo metropolitan authority reported 727 new COVID-19 cases Monday, which was the 30th straight day the tally was higher than the previous week. The count was 502 last Monday.

The games open Friday with no fans in nearly all event venues, including at the opening ceremony, amid a state of emergency in Tokyo, and a slower than hoped for vaccine rollout. Japanese authorities said Monday 21.6% of the nation's 126 million population is fully vaccinated.

The total of Games-related infections was officially 58 since July 1 before the two new cases were announced. They should be added to the official tally on Tuesday.

These resulted from 22,000 people arriving in Japan since July 1 with 4,000 of those staying in the village, Ducrey said. About 11,000 athletes are scheduled to compete at the Tokyo Olympics.