Olympics organisers battled an array of persistent problems as the Games entered its second week on Saturday, from a lurid green diving pool to competitors taken to the wrong venue, and a long-distance swimming pontoon swept away by the waves.
The refusal of the Olympic diving pool to return to a more appealing blue hue has baffled technicians and competitors alike after it was pumped full of chemicals since turning a cloudy green colour on Tuesday.
The colour and acrid smell of the pool have prompted jokes on the internet and complaints from competitors and have become a symbol of the organisational problems dogging South America's first Games, which come as Brazil struggles with deep recession and political upheaval.
On Saturday, Olympics organisers finally concluded the strange colour was due to a mix-up over pool chemicals. A contractor dumped 80 litres of hydrogen peroxide into the water on the opening day of the Games, without informing them.
The chemical, which is used to keep pools clean, neutralised the chlorine that organisers were using to keep the pool blue, allowing algae to flourish, they said.
Organisers said on Saturday they would spend 10 hours draining and replacing the water in the waterpolo pool, which has gone from green to a cloudy blue. The same pool is needed on Sunday for the start of synchronised swimming where competitors need to see each other under water.
"Of course, it's an embarrassment," said Rio 2016 spokesman Mario Andrada, who originally said the problem would be fixed on Wednesday. "This was probably the only issue that we were unable to solve quickly," he told reporters.
The organisers will not drain the diving pool and instead continue with chemical treatment, as the discolouration did not seem to concern competitors in that sport as much. The diving competition will run throughout the second week of the Games.
By Saturday afternoon, the diving pool remained a murky green.
"If the pool doesn't change, we do!" wrote German diver Stephan Feck on his Facebook page above a photo of he and his teammates, coloured green.
As the Games reach their midway point, the list of sporting achievements in Rio is growing, from a slew of world bests by the all-conquering US swimmers to the performance of the first-ever refugee team at the Games, and successes in the velodrome dubbed a 'world record factory' by organisers.
The sporting excitement has gone some way to turning the page on a doping controversy that led to scores of Russian competitors from several sports being banned from the Games.
Russian track and field suffered a final humiliation on Saturday when the sport's governing body suspended long jumper Darya Klishina, removing from competition its only competitor to have survived the athletics blanket ban.
Poor attendance at many Olympic venues and concern over booing by Brazilian fans more accustomed to football have raised eyebrows.
Organisers expect that when Jamaican sprint legend Usain Bolt takes to the track for the 100 metres final on Sunday, fans will pack the 60,000-capacity stadium.
Yet in addition to thin crowds, security concerns fed by a spate of robberies of fans and competitors as well as organisational glitches with transportation around Rio have stirred frustration.
Organisers' decision to spread the Games across a number of sites around Rio de Janeiro, a city of more than 12 million people, in an effort to share the infrastructure benefits of the Games has been criticised by competitors and fans for the long distances and hours spent in traffic.
Andrada said a group of swimmers had risked missing their races after a bus driver meant to have taken them to the Olympic pool misheard the acronym used for the site and drove them instead to the athletics stadium on the other side of town.
And organisers said they had a standby pontoon for the 10-km marathon swimming after the original pontoon was swept away amid big waves and broke up on Copacabana beach. The men's and women's races are due to take place on Monday and Tuesday.