Two South African soccer players became the first athletes inside the Olympic Village to test positive for COVID-19, and other cases connected to the Tokyo Games were also confirmed Sunday, highlighting the herculean task organizers face to keep the virus contained while the world’s biggest sports event plays out.

The positive tests came as some of the 11,000 athletes and thousands more team officials expected from across the globe began arriving, having traveled through a pandemic to get to Tokyo.

They’ll all now live in close quarters in the Olympic Village on Tokyo Bay over the next three weeks.

International Olympic Committee President Thomas Bach said last week there was “zero” risk of athletes passing on the virus to Japanese or other residents of the village. But that bold statement was already being tested.

The Olympics, which were postponed for a year because of the pandemic, are set to officially open Friday and run until Aug. 8.

The two soccer players and a team video analyst who also tested positive had been moved to “the Tokyo 2020 isolation facility,” the South African Olympic committee said. The rest of the squad members and officials had also been quarantined.