Sprinter Blessing Okagbare is out of the Tokyo Olympics after being suspended for failing a drugs test.
The Nigerian - a rival to Great Britain's Dina Asher-Smith - had won her 100m heat on Friday and was due to race in the semi-finals on Saturday.
The Athletics Integrity Unit (AIU) said the 32-year-old had tested positive for a human growth hormone following an out-of-competition test on 19 July, reports the BBC.
The AIU said Okagbare was notified of her provisional suspension on Saturday.
It added it would not be making any further comment at this stage.
Okagbare, Olympic long jump silver medallist in Beijing in 2008, had posted a time of 11.05 seconds in her 100m heat and was set to line up against Asher-Smith and Jamaica's Elaine Thompson-Herath in the first semi-final.
The news comes two days after 10 other Nigerian athletes were declared ineligible for the Games.
The AIU ruled they were unable to take part because of non-compliance with out-of-competition drug testing requirements in the run-up to the Olympics.