Olympic cycling champion Tyler Hamilton has been banned for two years following positive tests for blood doping.
Hamilton failed tests at the Olympics and the Tour of Spain
Hamilton tested positive at the Tour of Spain on 11 September and will forfeit all competitive results from that date.
The US Anti-Doping Agency announced the suspension on Monday, but the American will keep his Athens gold after a "B" sample - also positive - was destroyed.
However, the 32-year-old has hired a lawyer and will take his case to the Court of Arbitration for Sport.
"This is far from over," said Hamilton, who has always denied using performance-enhancing drugs.
Hamilton first tested positive for a blood transfusion after winning the time trial in Athens last summer but the case was dropped because the B sample was frozen.
"Following the full hearing, the majority of the panel rejected Hamilton's defenses and found that his positive sample was 'due to a homologous blood transfusion,'" said the USADA.
"Based on blood screens taken in 2004, the International Cycling Union (UCI) warned Hamilton and his team that Hamilton was suspected of manipulating his blood.
"Following these warnings, UCI target-tested Hamilton and he tested positive."
Blood doping is a means of enhancing endurance by increasing the amount of oxygen-carrying red blood cells using one's own blood or a donor of the same group.