Sated by silver, Kyle Chalmers believes his Chinese conquerer is drug-free after the Australian swim ace was beaten to another Olympic title in Paris.
China's Pan Zhanle broke his own world record to pip Chalmers in Wednesday night's 100m freestyle final.
"I do everything I possibly can to win the race and trust everyone's doing the same as I am, staying true to the integrity of sport," silver medallist Chalmers said.
"I trust that ... he (Pan) deserves that gold medal."
China's team has been under increased scrutiny since revelations 23 swimmers tested positive to a banned substance before the Tokyo Olympics three years ago.
Pan was not in the group of 23 which was allowed to compete in Tokyo after world anti-doping authorities accepted China's explanation the swimmers had eaten contaminated food at a team hotel.
In Paris, Pan clocked 46.40 seconds, 0.40s inside his previous benchmark, to win with a time Chalmers (47.48) described as "crazy".
"It's a time I never dreamed or saw as possible," Chalmers said.
"The last 15 metres ... I thought I could be dead last because he was so far ahead of me."
Chalmers now has consecutive Olympic silver medals to follow his 2016 gold in the blue riband event.
His compatriot Zac Stubblety-Cook also won silver on Wednesday night in an attempted defence of his men's 200m breaststroke title.
And it took an Olympic record by French megastar Leon Marchand to beat him.
Stubblety-Cook finished in the wake of Marchand, who collected two gold medals within an hour amid raucous support from his parochial home crowd at the La Defense Arena.
"It didn't feel like a swim meet, it felt like a rugby game ... you can't hear yourself think," Stubblety-Cook said.
Marchand triumphed in the 200m butterfly before his breaststroke victory and the Parisian now has three golds medals at his home-town Games.
In Wednesday night's women's 100m freestyle final, Australia's pre-race favourite Mollie O'Callaghan (fourth) and compatriot Shayna Jack (fifth) missed the medals.
"I expected a lot more," O'Callaghan said.
"But at the end of the day you've got to suck it up and wait another four years."
O'Callaghan was bidding to become just the third woman to complete a 100-200m freestyle golden double at the same Olympics.
But Swedish great Sarah Sjostrom, a 30-year-old at her fifth Olympics, trumped the field to win.
O'Callaghan, who won the 200m freestyle gold and also featured in Australia's victorious 4x100m freestyle relay team in Paris, admitted anxiety leading into the 100m final.
"I was really nervous heading into this, didn't have a lot of sleep over the past few days," she said.
"I knew it was going to be at tough race ... if you stuff something up, it costs you."
Jack, also a part of Australia's golden 4x100m freestyle relay team on Saturday night, missed the Tokyo Games after serving a two-year doping ban.
"I wanted to walk out, soak up the crowd and enjoy my family being in the stands," Jack said.
"I tried to reflect but absorb the fact I'm here as an Olympian. A couple of years ago I never thought that would be possible."
Australians Liz Dekkers (ranked fourth) and Abbey Lee Connor (seventh) both secured spots in the women's 200m butterfly final.
And American Katie Ledecky added to her legend with victory in the women's 1500m freestyle - the seventh Olympic gold medal of her glittering career.
Australian Moesha Johnson was sixth and finished 32.68 seconds behind Ledecky, who is also chasing a fourth-successive 800m freestyle gold.
Dolphins Jenna Strauch and Ella Ramsey failed to progress to the women's 200m breaststroke final.
