The International Olympic Committee has stripped US runner Crystal Cox of her gold medal from the 4x400m relay at the 2004 Athens Olympics for doping.
Cox admitted in 2010 to using anabolic steroids and accepted a four-year suspension and disqualification of her results from 2001 to 2004.
The executive board has now formally disqualified Cox and taken away her gold medal, but is yet to decide whether to act against her team.
The IOC said the rules of the International Association of Athletics Federations determined whether to disqualify the US team from the gold, but it was not clear if those rules were in effect at the time.
Under international rules, an entire relay team can be disqualified because of the doping of one member, even an alternate.
Cox ran in the preliminaries for the American team but Sanya Richards ran the final along with Dee Dee Trotter, Monique Henderson and Monique Hennegan.
"It is now within the remit of the IAAF to interpret its rules as to whether the disqualification of the athlete would have any effect on the results of the US relay team," the IOC said.
If the US is stripped of the victory, Russia would move from silver to gold and Jamaica from bronze to silver.
In a separate case dating back to the 2000 Sydney Games, the IOC has reallocated the medals removed from the US men's 4x400m relay team because of admitted doping by the late Antonio Pettigrew.
The IOC stripped the US team - including Michael Johnson - of the medals in 2008 after Pettigrew's admission but had postponed reallocating the medals pending an investigation.
Pettigrew died in 2010 from an overdose of sleeping pills.
The decision means Nigeria is elevated to the gold, with Jamaica moving up from bronze to silver and the Bahamas from fourth to bronze.