Around 20,000 soccer fans will be attending UEFA's Super Cup final in Budapest on Thursday, in what may be a big test for sports in Europe.
It's less than a third of the stadium's capacity and UEFA says strict hygiene measures are being followed.
But a leading Hungarian epidemiologist, Andras Csilek, tells Reuters it's still a huge risk.
"If the Hungarian health care leadership say together with the Hungarian government and UEFA that this can be done then obviously it can be done. But nobody knows where this leads, but if it is an experiment, that is wrong. You don't experiment with people."
The game officially starts the new European soccer season. This year Champions League winners Bayern Munich are playing Sevilla, who won the Europa League.
The newly completed Puskas Arena has been viewed as something of a pet project for Hungarian Prime Minster Viktor Orban.
Bayern, from Bavaria in Germany, took time ahead of the match to pose for their traditional team photo in full lederhosen, while there was a warning form Bavaria's own premier warning fans to stay away from Budapest.
Experts including Csilek have traced a surge in Italy's public health crisis back to soccer matches in February and similar conclusions were also reached after UEFA allowed Atletico Madrid fans to travel to Liverpool for a Champions League match in March.
Hungary's government says it's trying to "keep the country going" to avoid an economic disaster, with Orban's chief of staff saying on television that supporters will be “safer to attend than almost any other social gathering”.