British tennis star Greg Rusedski has tested positive for the banned substance nandrolone.
The British number two confirmed that he had failed a drugs test, but pleaded his innocence.
"In response to media inquiries, I can confirm that a sample has tested positive for a low level of nandrolone," he said in a statement.
The 30-year-old will face a hearing in Montreal on 9 February.
"I shall attend and I fully expect to be found innocent. I do not and have not taken performance-enhancing drugs," he added.
The test dates from a tournament he played in the summer in Indianapolis during an injury-plagued season when he competed in only six tournaments.
He has only just returned to tennis after an absence with back, knee and foot injuries.
The Canadian-born player lost the second match of his comeback in Adelaide on Thursday.
The highpoint of his career was a run to the final of the US Open in 1997 when he lost to Australia's Pat Rafter.