Fans spotted what US star Noah Lyles did just seconds before finishing the men's Olympic 200m final on Thursday evening.
Lyles, who was one of the favourites to win the event and pick up his second gold of the Games after winning the 100m, took third and the bronze medal.
He ran a time of 19.70, which was 0.17 off his season best, but even matching that time would not have seen him finish ahead of gold medal winner Letsile Tebogo.
It had been reported pre-race that Lyles was suffering from an illness, although it was not disclosed at the time what the illness was.
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But just minutes after the 200m final finished, it was confirmed that the 100m champion had been diagnosed with COVID-19 on Tuesday morning.
Lyles received medical attention on the track, and was taken away in a wheelchair.
Olympics organisers do not have mandatory rules when it comes to COVID, meaning Lyles could race as long as he felt able to.
After the race, Tebogo said in a press conference that he could not be the face of athletics as he was not an 'arrogant or loud person' like Lyles - although some African reporters have suggested that the remark was not to be taken literally, with English being the Botswana sprinter's second language, and was more likely regarding the positive energy of the American.
Prior to the race, Lyles showed off that positive energy - which has divided some fans - by sprinting across the width of the track in front of the other competitors when his name was announced.
He then walked towards the fans and acknowledged them, receiving a huge round of applause afterwards.
Speaking after the race, Lyles spoke about the effects that the COVID-19 diagnosis had on his race: "I have definitely had better days but I am walking around again.
"I was quite light headed after that race and the chest pain was definitely active.
"After a while, I was able to catch my breath and get my wits about me. I am feeling a lot better now. It definitely affected my performance."
Topics: United States, Athletics, Olympics
Ryan Smart