Serbia's men's pair capsized on the Rodrigo de Freitas Lagoon as choppy waters complicated things for rowers on the first day of competition.
Milos Vasic and Nenad Benik ended up in the water as their boat overturned about halfway through their heat, which was easily won by New Zealand's Eric Murray and Hamish Bond.
After a quiet morning the wind picked up and athletes were struggling to keep their oars from bouncing off the waves on the 2-kilometer course.
Britain's Alan Campbell, who won his heat in the men's single sculls, said the conditions took him by surprise.
"He needs to spread his arms a bit more to protect us," Campbell said, nodding toward the iconic Christ the Redeemer statue towering over the rowing venue.
The race continued as safety crews rushed out to aid the stranded Serbian pair, although for some reason they remained in the water almost five minutes after they capsized.
Fourth place does allow the crew to go through to the repechage, although rules state that the team must finish the race in order to do so.
The sight of Vasic and Bedik would normally be nothing more than comical, but given the alarming reports that emerged in the build-up to the Olympic Games in Rio about the levels of contamination in the water where the rowing and sailing takes place, the pair could be in a spot of bother.
It was claimed in a report commissioned by The Associated Press that the water in the Olympic and Paralympic venues contained 1.7m times the level of viruses that would normally be considered a concern in Europe and the United States due to raw sewage being pumped into a nearby canal.
It was claimed in the report that just three teaspoons of open water would mean a person would be "almost certain" of contracting a virus.
Measures were taken by Team GB to minimise the risk of catching any viruses by immediately showering after training, keeping water bottles in protective containers and brushing teeth with bottled water only.