|Rodgers faces penalties ranging from a warning to a months-long ban [GALLO/GETTY]
Former United States 100 metres champion Mike Rodgers has tested positive for a banned stimulant.
Rodgers' hopes of making the World Championships in Daegu, South Korea next month are now in the balance.
"Mike made a mistake," his agent, Tony Campbell, told the Reuters news agency.
"He went to a club with some friends in Italy and he thought he was drinking a Red Bull (energy drink) but he got one of those energy drinks that had a stimulant in it."
Rodgers, the year's fourth fastest 100 metres runner, said on his Twitter account he had failed a test.
"Tested positive for stimulant in an energy drink," he tweeted. "I'm just trying to get a hearing before worlds so I can know my fate."
Rodgers was named in the US team in the 100 metres and 4x100 relay. He finished third in the 100m at the US world championship trials in June.
Penalties for a positive test for stimulants can range from a warning to a suspension of several months.
Campbell said Rodgers, 26, had not been suspended by USA Track and Field (USATF) as of Saturday.
USATF officials could not be reached for immediate comment on Rodgers's status for the World Championships which begin on August 27 in Daegu, South Korea.
Rodgers was yet to have his second "B" sample tested, Campbell said, adding that he understood the result would not come until two days after USATF finalised its team on Monday.
"It is a bad situation for us now," Campbell said, referring to the timing of the failed test.
"I would surmise (USATF) are going to leave Mike in there (on the team) until the final verdict is in," he said.
"I don't want anyone to think Mike is a druggie. It was a stimulant. It was not steroids or anything of that nature."
Campbell said Rodgers's positive test had come last month at a meeting in Lignano, Italy, where the US team had a relay training camp.
He said Rodgers had passed all previous tests including a blood test several days ago.