A doping row involving Chinese athletes may prove to be a tinderbox at the Olympic swimming meet, where the United States faces the biggest challenge to their reign in decades.
Some of the world's best in the sport have criticized anti-doping authorities and raised concerns about the competition's integrity following revelations in April that 23 Chinese swimmers were allowed to compete at the Tokyo Games despite testing positive for the banned heart medication trimetazidine (TMZ).
The World Anti-Doping Agency accepted the findings of a Chinese investigation that the test results were due to contamination from a hotel kitchen the team was staying at.