Officials have ruled that US athlete Jerome Young was guilty of doping and should be stripped of his Olympic gold.
Young led America to 4x400m glory at the 2000 Olympics
Young tested positive for nandrolone in 1999 but was cleared for the 2000 Olympics by US officials and went on to lead the 4x400m relay team to gold.
But the Court of Arbitration for Sport said Young should have been banned for two years, ruling him out of the Games.
The court declined to rule whether the rest of the squad - including Michael Johnson - should lose their medals.
4x400m RELAY TEAM IN SYDNEY
It said that decision should rest with the International Olympic Committee and IAAF, the governing body of athletics - but that it was not a foregone conclusion.
"The panel does not necessarily accept that, in the unusual circumstances of the present case, this consequence must follow," read the judgement.
If the US team is disqualified, the medals would be
readjusted. Nigeria would be awarded gold, Jamaica silver, and the Bahamas bronze.
Last month, the British team was stripped of its relay
silver medal from the 2003 world championships after Dwain Chambers was banned for two years.
The court ordered USA Track and Field, which originally cleared Young to race, to pay £4,387 (10,000 Swiss Francs) costs of the case.
It said the original decision by the USATF's Doping Appeals Board to clear Young was wrong and based on an "inadequate and irrelevant" theory put forward by Young's expert witness, which had "no scientific basis".
Young's expert had argued that nandrolone metabolites pass through a person's body so slowly, that it was impossible for Young to have given a clean test six days after a positive result with such high readings.
Young was not at the hearing.
But in a statement issued later on Tuesday he said the judgement was unfair.
"I have maintained since June 1999 (that) I have never taken a prohibited substance," Young said in the statement issued by his lawyers. "Nothing has changed to justify CAS's decision today."
He added: "I believe that today's CAS decision is fundamentally unfair - I was exonerated in 2000 by a panel of three independent and objective arbitrators who considered the evidence before it and concluded that USA Track & Field failed to prove its case against me.
"I was told by USA Track & Field (USATAF) back then that my case was closed and I was told by CAS on January 10 2003, that my case was closed."
The IAAF, which battled for years to force USATF to provide details of the case and took the case to arbitration, was pleased with the verdict.
"The IAAF is delighted that this case that dates back to
1999 has finally been resolved with a decision that
vindicates our position," said IAAF spokesman Nick Davies.