Justin Gatlin was one of 420 athletes to take part in a test event at an empty Olympic stadium as preparations continue for the delayed Tokyo games.
The event was held behind closed doors with Tokyo under a state of emergency due to a rise in coronavirus cases.
A small protest outside the stadium called for the Games to be cancelled.
American sprinter Gatlin, who was one of nine international athletes involved and won the men's 100m, said daily testing and use of a bubble showed the games could be staged successfully and without adding to Japan's coronavirus infections.
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