Peruvian second division side Hijos de Acosvinchos were playing promotion rivals Sport Ancash in a key match at San Alfonso de Ate when the affected players fell to the turf during the second half.
Defender Andy Salinas was first to go when he fainted after 65 minutes to the alarm of his team-mates, with Juan Luna, Martin Reategui and Luis Coello all collapsing soon after.
The quartet were rushed to hospital where doctors confirmed that their blood contained benzodiazepine, a common sedative often used for treating insomnia.
The match was eventually restarted, with Sport Ancash going on to win 3-0 to secure promotion to the top tier of Peruvian football.
But the losing side are convinced that their players were nobbled by spiked water, and are set to launch an appeal.
"My boys say Ancash medical staff gave them a liquid which made them feel dizzy and faint," explained Hjios de Acosvinchos manager Americo Ibanez.
"When they returned the bottles so the other team drank from them as well, someone snatched them out of their hands.
"We want the authorities to investigate this and prove where this substance came from. We're intending to launch a formal complaint."
Aldrin Perez, president of Hijos de Acosvinchos, also claimed that a member of the Sport Ancash support staff had given water to the affected players at half-time - and that the same water had not been given to the home team's players.
But Sport Ancash president Pepe Mallqui claimed that the players had collapsed after eating a big meal before the match on Sunday.
" They ate barbecued chicken with spices and ended up taking indigestion tablets afterwards," he said.
"I'm sure these four men fainted because of that and the physical effort they put in."
- Sport Ancash
- Hijos de Acosvinchos