The men's triathlon at the Olympic Games in Paris has been postponed due to water-quality levels in the River Seine.
The men's triathlon had been set to take place on Tuesday morning, with the women's event to be held 24 hours later.
The decision has now been taken to move the men's race to Wednesday as well.
It has been rescheduled to take place at 10.45am local time (9.45am BST) on Wednesday, after the women's race which is scheduled to take place at 8am (7am BST).
A statement from World Triathlon said Friday remains a contingency day if one or both of the races are unable to go ahead.
"Tests carried out in the Seine today revealed water quality did not provide sufficient guarantees to allow the event to be held," World Triathlon said in a statement released on Tuesday morning.
"Despite the improvement in the water quality levels, the readings at some points of the swim course are still above the acceptable limits."
Training in the river had been cancelled over the weekend and again on Monday due to unsafe levels of pollution caused by the heavy rain that blighted the Olympic opening ceremony on Friday and initial outdoor events on Saturday.
Paris has a combined sewer system, meaning both wastewater and stormwater flow through the same pipes.
When there are periods of heavy rainfall, the pipes can reach capacity and this wastewater – including sewage – overflows into the River Seine instead of being sent to a treatment plant.
Open water swimming and triathlon events were due to take place in the Seine, more than 100 years after swimming in the river was banned in 1923.
Earlier this month, France's sports minister Amelie Oudea-Castera swam in the Seine alongside Paralympic triathlon champion Alexis Hanquinquant, who won gold in the men's PTS4 event at Tokyo 2020, to show people it was clean enough for the Olympic swimming events.
Paris mayor Anne Hidalgo also took a dip, joined by Paris 2024 chief Tony Estanguet, but there was no sign of President Emmanuel Macron who had suggested he would also take the plunge.
Hildago had originally planned to swim in the river in June but was forced to delay after tests indicated the presence of faecal matter 10 times higher than authorised limits.
Paris officials have spent €1.4bn in a bid to improve water quality ahead of the Games.
GB has strong medal contenders in the event. Britain's Alex Yee is one of the favourites for gold in the men's race while Beth Potter is the reigning women's world champion.
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