Guillermo Canas, who withdrew from the men's singles draw, has told two Argentine newspapers he is under investigation by the ATP Tour for allegedly testing positive for a banned substance.
The ATP declined to comment and there was a similar response from the International Tennis Federation, which said that it had only seen the newspaper reports.
Canas told La Nacion and Clarin he was pulling out of Argentina's Davis Cup tie against Australia because "I'm being investigated by the ATP for doping. I don't know what happened. I've been over everything I've taken with my team and there is nothing which is prohibited.
"I trust the system. I hope it's a mistake and nothing more."
Both newspapers said the alleged positive test had happened at an ATP tournament in Acapulco, Mexico, in February.Reuse content