Sprinter Blessing Okagbare is absent from the Tokyo Olympics after being suspended for failing a doping control.
The Nigerian, rival of Britain’s Dina Asher-Smith, won her 100m on Friday and was due to play in the semi-finals on Saturday.
The Athletics Integrity Unit (AIU) said the 32-year-old tested positive for human growth hormone following an out-of-competition test on July 19.
AIU said Okagbare was informed of her provisional suspension on Saturday.
He added that he would not make any further comment at this point.
Okagbare, Olympic silver medalist in the long jump in Beijing in 2008, clocked 11.05 seconds in her 100m series and was set to face Asher-Smith and Jamaican Elaine Thompson-Herath in the first semi-final .
The news comes two days later 10 other Nigerian athletes were declared ineligible for the Games.
The IAU ruled that they were unable to participate due to non-compliance with out-of-competition doping control requirements in the run-up to the Olympics.
Otieno Odhiambo suspended for positive test for banned substances
Elsewhere, Kenyan 100m sprinter Mark Otieno Odhiambo will also not compete in the Games after testing positive for a banned substance.
He was scheduled to compete in the 100m heats on Saturday, but was provisionally suspended.
Otieno Odhiambo denies any knowledge of the violation and has requested a retest of his B urine sample.
He told media earlier this month that he was eager to prove that Kenya can do well in both the sprint distances and the long distance events.