Soon enough they will be playing rugby again at the Arena in La Défense. It’s a kit stadium and after the Paralympics finishes, the two Olympic pools inside it will be drained, packed away and put up again in their new, permanent, locations. The scaffolding grandstand will be taken down, the pitch laid down and the posts reinstalled ready for Racing 92’s next home game. Maybe by the time their new signing Owen Farrell is standing ready for the kick-off, the crowd’s great shout of “Allez!” every time Léon Marchand breasted the water this past week will have finally finished echoing around the rafters.

At the start of the Games, the 22-year-old was a richly gifted kid, burdened with an almost unfathomable weight of expectation. France does not have a bona fide star to light up the athletics at the Stade de France, which means Marchand, who won his first world championship title in 2022, came as the biggest hope the host nation had in the two main Olympic sports.

Marchand’s parents, both Olympic swimmers, encouraged him to move to the US to get away from all the attention, which only meant the college swimming circuit all of a sudden had a French press pack for the season.

Related: Adam Peaty says he may retire … and hits out at ‘cheating’ Chinese swimmers

This kind of pressure has broken athletes before. China’s world champion hurdler Liu Xiang, the face of the Beijing Games, flopped out of the heats. Britain’s world champion triple jumper Phillips Idowu went missing during the run‑up to London 2012 then got knocked out in the rounds. But Marchand – who, for all his success, had never won an Olympic medal before, much less performed in front of a crowd quite like this one – rose to meet the moment in a way very few athletes have. In eight days he won four gold medals, set four Olympic records and then helped the French team to win bronze in the 4x100m medley, just for good measure. If he could have done all four legs himself, they would probably have won that one, too.

A swimmer has not owned an Olympics quite like this since Michael Phelps won eight gold medals in Beijing. Every session was sold out, every seat in the media section taken and every stroke stoked great roars of excitement from the French public, who gathered around TV screens in homes, bars, and restaurants around the country to watch. His finals were appointment viewing. He became the great home hero of the Games. And he’s not done. “This is just the beginning,” Marchand said this weekend. “My next goal is Los Angeles 2028.”

The sport needed it. The Olympics started under a cloud, when reports broke that 23 Chinese swimmers had failed drug tests for trace amounts of the banned performance-enhancing drug TMZ and a row broke out between the US Anti-Doping Agency and the World Anti-Doping Agency about the handling of the case.

Eleven of the 23 were picked to compete here in Paris. One, the breaststroker Qin Haiyang, was subsequently found to have failed another test for a different drug in similar circumstances. Qin said he was the victim of a “European and American plot”, and promised to win medals to “silence the sceptics”.

He did not, until the last night, when he was part of the men’s 4x100m medley relay team that beat the USA for the first time in Olympic history. The 11 won four individual medals and five more in the relays, including that famous gold. Athletes who live by the idea that they are strictly liable for everything in their bodies, however it got there, were resentful. The atmosphere around the pool was tense, and uneasy, the Chinese felt discriminated against and the clean swimmers on their team, including their new world record-holder Pan Zhanle, complained about the way they were being treated.

The athletes’ anger was best aimed at their sport’s governing bodies. Paris was the fourth Games in a row when the swimming competition has been overshadowed by doping scandals. “It just seems like there is cycle after cycle of concerns and questions,” said the USA breaststroker Nic Fink.

World Aquatics has work to do to win back the confidence of the athletes. Which is a pity, because in the water the sport has seldom been better. The USA moved to the top of the medal table after winning one last gold in the final women’s 4x100m medley, but there is an irresistible sense, as Caeleb Dressel said, that the rest of the world is catching up to them.

Related: ‘Face of Games’ Léon Marchand gets Paris jumping by storming to medley gold

The slow pool, which was shallower than usual, actually made the races unpredictable and exciting. The Games included what were probably the last great races of a series of champion swimmers, such as Dressel, Adam Peaty, Florent Manaudou, and Emma McKeon, as well as more famous wins for others, such as Katie Ledecky and Sarah Sjöström. But really it was all about the younger generation, not just Marchand, but Pan – whose 100m win was described by Dressel as one of the two greatest swims he had seen – Canada’s Summer McIntosh, Australia’s Mollie O’Callaghan, Romania’s David Popovici, and Ireland’s Daniel Wiffen.

You can only hope that in the years ahead they will not be let down by the men – and they are largely men – who run their sport, in the same way the older generation was in the years just gone.