A doctor who has treated Tiger Woods, baseball star Alex Rodriguez and other elite athletes has admitted charges of bringing illegal drugs into the US.
Canadian Anthony Galea has been charged with smuggling drugs including human growth hormone (HGH) into the country.
The Toronto-based physician, not licensed to work in the US, was said to have treated 20 professional athletes from October 2007 to September 2009.
His plea means a trial, revealing his clients, will not be held.
The indictment did not identify any clients, but prosecutors in the US city of Buffalo said they included golfers, professional baseball and American football players.
Golfer Tiger Woods said recently that he had been treated by Galea, but categorically denied using performance-enhancing drugs.
Galea, 51, is due to be sentenced on 19 October. He could face up to two years in prison.
Among the charges, Galea was accused of unlawful HGH distribution, lying to US officials, conspiracy to defraud, smuggling and interstate commerce with the unapproved drug actovegin.
Actovegin, a drug extracted from calf's blood, is illegal in the US and not approved for use in Canada.
Galea became the focus of Canadian and US authorities' attention in September 2009, when his assistant, Mary Anne Catalano, was stopped at the border in Buffalo with a small quantity of human growth hormone, Actovegin and vials of foreign homeopathic drugs.
She is due to be sentenced later this month and has pleaded guilty already to one count of lying to border agents.