South Africa's Olympic football coach fears his players' health could be at risk after being forced to isolate at the Tokyo Games, citing Christian Eriksen's traumatic ordeal at Euro 2020.

The team head into their opening game against Japan on Thursday in disarray after two players and a video analyst tested positive for coronavirus following their arrival at the Olympic Village.

Twenty-one members of the team contingent were named as close contacts on Monday, forcing them to miss two training sessions as they isolated in their rooms.

Coach David Notoane fears the lack of time to acclimatise in hot and steamy Tokyo could put his players at risk.

He pointed to the example of Denmark midfielder Eriksen, who collapsed at the European Championship last month after suffering a cardiac arrest before being resuscitated.

"You saw what happened in Euro 2020 when Denmark played," Notoane said on Tuesday.

"One can only hope and pray that with the players having been out of activity for a long time since we arrived here, we don't experience something like that."

"Maybe we haven't acclimatised enough to these conditions as we would have liked to," he added.

Athletes designated as close contacts at the Games must comply with strict guidelines in order to be allowed to train, including staying in their rooms and using special transport.

But the players will be eligible to play on Thursday if they test negative for the virus six hours before the game.

Notoane said he had 17 players at his disposal, and was thankful the game had not been called off.

"The worst-case scenario could have been that we were suspended from the tournament, or we don't have enough team members to participate in the tournament," he said.

Five people have tested positive in the Olympic Village so far, heightening fears that the influx of thousands of athletes, officials and media will add to a spike in cases in Japan.

But Japan defender Maya Yoshida was unconcerned about facing the South Africans in their tournament opener.

"I've played for the past year in a controlled environment where anyone who tested positive couldn't play," said the Sampdoria defender.

"Personally, I don't see any issues with playing in this environment. We're under restrictions at the hotels to make sure that we're safe, so I personally don't feel unsafe."