“Any doubt is just a joke. Stress only makes us stronger,” Qin Haiyang – a part of China’s history-making men’s 4x100m medley quartet posted after their unprecedented victory over the US on Monday.

Qin’s seeming defiance came at the tail end of what has been a challenging time for China in the pool.

Some of the country’s top swimmers – including Qin and his relay teammate Sun Jiajun- have been in the spotlight after a slew of doping allegations, followed by contentious US claims that the World Anti-Doping Agency (Wada) was covering it up.

They were among 23 Chinese swimmers who reportedly returned positive doping tests prior to the Tokyo Olympics.

And although Chinese swimmers have been drug-tested twice as much as some other nations this year before heading to Paris, their performances have been met with scepticism.

Right after the medley event on Monday, Team GB’s Adam Peaty opened his fire on the Chinese team, saying “there’s no point winning if you’re not winning fair”.

Swim legend Michael Phelps who has been vocal about doping issues also doubled down. “If you test positive, you should never be allowed to come back and compete again, cut and dry,” he told news agency Associated Press. “I believe one and done.”

To the Chinese swimming team and their millions of fans back home, however, the victory brought joy and vindication.

The hashtag “China winning gold medal at 4x100m medley relay” was viewed 760 million times on Weibo.

“China’s gold medal are squeaky clean, we won it with our competence!” A comment racked up more than 8,000 likes on Weibo reads.

“It’s been so hard for the Chinese swimming team,” read another top comment.

The pressure has indeed been immense.

And this has been reflected in comments by China’s new breakout star Pan Zhanle, who swam the crucial anchor leg of the relay and also won the men’s 100m freestyle final with a new world record.

After his 100m win last week, Pan – who had not been among the revealed names of positive test results – told Chinese media that he felt that the team was “looked down on” by some foreign swimmers, adding that Australia’s Kyle Chalmers had snubbed him when he tried to say hello.

And although Pan was not among those who tested positive, his record-breaking performance was questioned by former Australian Olympic swimmer Brett Hawke who posted on Instagram that it’s not “humanly possible to beat that field”.

German athlete Angelina Köhler also questioned the bronze-winning performance of China’s Zhang Yufei – who was also among the 23 who had previously tested positive . Köhler who did not make the podium, reportedly told reporters after the swim that “stories like that always have a bad flavour”.

Zhang, who won a silver and five bronzes in Paris, was also defiant.

“Why should Chinese swimmers be questioned when they swim fast? Why did no one dare to question USA’s Michael Phelps when he got eight gold medals?” she asked in a press conference.

The tension has spilled beyond the pool too. China’s anti-doping agency (Chinada) released a statement on Tuesday, accusing its US counterpart Usada of displaying double standards.

The press release highlighted the case of US sprinter Erriyon Knighton. Knighton, a world silver medallist who is competing in the men’s 200m sprint this week, was not suspended after testing positive for the banned substance trenbolone earlier this year. Like in the case of the Chinese swimmers, the arbitrator had found the result was likely caused by contaminated meat.

Meanwhile Chinese fans are also taking matters to their own hands.

Adam Peaty’s Instagram account was flooded with angry comments in the past day. Even his girlfriend’s account was not spared. “Curious why you’re only attacking China but none of the other countries that won ahead of you as well… pretty weird,” a top comment under Peaty’s most recent post reads.

Brett Hawke, who is now a swimming coach, has also been hit with angry comments on his Instagram account. He has now deleted the video he first posted about Pan and limited comments on his posts.

Instead, on a recent post about the men’s medley results, his caption simply said: “Chinese men are victorious!”