Maurren Higa Maggi, the world's top-ranked women's long jumper, has been suspended from competition.
Maggi is out of the Pan-Am Games
The Brazilian is being investigated by the International Association of Athletics Federations (IAAF) for alleged use of anabolic steroids, her coach said.
Maggi withdrew from the Brazilian team to compete in the Pan American Games, which began on Friday, 1 August, in the Dominican Republic.
Her coach, Nelio Moutra, said the IAAF has not confirmed whether Maggi tested positive but has suspended her while it investigates.
Fighting back tears during a press conference on Friday, Maggi claimed she would never intentionally use banned drugs, insisting: "I want to prove I am innocent."
The doping suspicion emerged after a routine test during the Brazil Trophy championship in Sao Paulo last month, according to Brazil's Olympic Committee.
Moura claimed Maggi might have tested positive because doctors applied a pharmaceutical cream after she received a cut during a hair
If the IAAF's investigation concludes she intentionally used banned steroids, Maggi faces a two-year suspension.
She won the gold medal at the Brazil Grand Prix in May, jumping 6.80m, and was third at this year's world indoor championships in Britain.