Adam Peaty may have swum his last race. After he and the British relay team of Matt Richards, Duncan Scott, and Ollie Morgan finished fourth in the 4x100m medley the 29-year-old Peaty said he “might have to step away from the sport” because “it hurts too much”.

This defeat was particularly painful. Two of the Chinese quartet that won gold, Qin Haiyang and Sun Jiajun, were among 11 swimmers allowed to compete at these Games even after it emerged they had previously tested positive for trace amounts of banned performance enhancing drugs. The positive tests were blamed on food contamination.

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If Peaty is done, he had things to say about it before he went.

“One of my favourite quotes in sport is that there is no point winning if you’re not winning fair,” Peaty said. “I think you know that in your heart. If you touch and you know you’re cheating, then you’re not really winning.

“So for me, if you’ve been ‘contaminated’ twice, I think as an honourable person you should be out of the sport.” Peaty put his own air-quotes around “contaminated” as he spoke. “But we know sport isn’t that simple.”

Peaty is one of several swimmers who feel there has been too much obfuscation in the way World Aquatics and the World Anti-Doping Agency handled the case.

“We’ve got to have faith in the system, but we don’t,” Peaty said. “It’s just got to be stricter. What I’ve said from the start is that it is fraud. If you’re cheating, it is fraud.” Scott nodded in agreement as Peaty spoke.

Peaty said he had no wish to criticise the rest of the Chinese team. “I’ve also been asked about people who weren’t contaminated and I respect that. I don’t want to paint a whole nation or a group of people with one brush. I think that would be very unfair.”

He said he had refused to speak out before now because he did not want to cause distractions for the team. Great Britain’s pool swimming team finished the Olympics with one gold and four silver. Peaty said he believed the relay quartet would use the defeat to the Chinese as motivation for the next Olympics, whether he is part of it or not.

“I think we’re going to use it to our advantage in the next four years, whether I’m there or not. I know these boys will carry that and we’ll see how they do in four years’ time. But,” he said, in a clear shot at the sport’s governing body, “the people that need to do their job, need to wake up and do it.”

Peaty’s remarks were echoed by Nic Fink who swam the second leg for the US team. “We have questions about the system and whether Wada is doing everything they can,” Fink said. “We know the ITA [International Testing Agency] is testing everybody all the time. They have been testing a lot here, which is good. But when a bunch of anti-doping agencies say: ‘Hey, what was the process here, how did that work?’, it raises red flags. So we just want more clarity and transparency. Nothing against the athletes competing. It’s questions about the system. Hopefully it gets ironed out because it just seems like there is cycle after cycle of concerns and questions.”

It was the first time the USA’s men had been beaten in the Olympic 4×100m medley relay final and the Chinese team of Xu Jiayu, Qin, Sun, and Pan Zhanle spoke afterwards about how badly they had wanted to break the US stranglehold on the event. “There’s no problem for the team. We follow the rules,” Xu said.

“I don’t want to have any excuses. We overcame some challenges and just like in the past we won some battles, this is something that’s rooted in the Chinese spirit.” They were led home by Pan, who turned in a blisteringly quick final split of 45.92sec.

Peaty, who has only just recovered from Covid, denied that his comments were motivated by being beaten into fourth. “It’s not about the podium,” he said. “We did our best job as a team, it may have been bronze, who knows, shoulda woulda coulda, who knows? But I’m glad I was able to come out of my illness this week and give my best and be fair. I don’t need anything else to do that, just my heart, that’s what sport is. And for me, being a man of faith, we can’t take any of this with us, but we can take our pride and we can take the memories we share with our families, knowing we did it true.”

The Chinese women’s medley team, which included two swimmers who had tested positive, won bronze behind Australia and the US quartet of Regan Smith, Lily King, Gretchen Walsh, and Torrie Huske, who won in a world record of 3min 49.63sec. The victory moved them to the top of the swimming medal table ahead of Australia.