Uruguay's Pablo Cuevas and Spain's Marcel Granollers were facing off against Britain's Jonny Marray and Canada's Adil Shamasdin in the men's doubles.
After an almost-four-hour, five-set marathon and down a break at 8-9, Cuevas and Granollers were denied a bathroom break by French umpire Aurelie Tourte.
A witness accused Cuevas of threatening to relieve himself into a ball can under the cover of a towel, prompting a code violation for unsportsmanlike conduct.