The Buenos Aires giants have been hit by a swathe of positive coronavirus tests, leaving them down to the bare bones and without a specialist goalkeeper against Independiente Santa Fe.
But the group match in South America's version of the Champions League was ordered to go ahead, with River Plate midfielder Perez – who started the 2014 World Cup final for his country – donning the gloves.
If that was not remarkable enough, the 35-year-old was named man of the match as the Argentinian club secured a scarcely-believable 2-1 win at El Monumental.
Fabrizio Angileri opened the scoring for the hosts in the third minute, with Julian Alvarez then firing home a stunning sixth-minute rocket.
Santa Fe upped the pressure in the second half and Kelvin Osorio pulled one back, but River Plate held on for a stunning victory in trying circumstances.