World record holder Qin Haiyang of China failed to qualify for the final of the men's 200m breaststroke at the Paris Games on Tuesday.
Qin, the 2023 world champion in the event, was considered one of the favourites for gold but finished with a time of 2min 09.96sec in his semifinal, 1.85sec behind the fastest qualifier Leon Marchand of France.
That time, over four seconds slower than his world record mark, left Qin tied for tenth with American Matt Fallon.
Qin set his world record time of 2:05.48 at the world championships in Fukuoka last year.
He had been fancied to battle for gold in both the 100m breaststroke final but faded to finish seventh.
Qin was reportedly among 23 Chinese swimmers who failed doping tests before the Tokyo Games but were cleared by Chinese authorities.
He and the Chinese authorities have denied any wrongdoing and stated that the swimmers had consumed contaminated food at a hotel where they were staying.