The 2011 Vuelta a Espana champion Juan Jose Cobo has been found guilty of an anti-doping violation, meaning Britain's Chris Froome could retrospectively be awarded the victory.
Froome finished second in 2011 and went on to win the first of his six Grand Tours in 2013 at the Tour de France.
If awarded the 2011 Vuelta, the history books would recognise Froome as Britain's first Grand Tour winner.
Bradley Wiggins has held the honour after his 2012 Tour de France win.
The news comes as Froome is in intensive care in a French hospital following a high-speed crash at the Criterium du Dauphine, in which he suffered a fractured right femur, a broken hip, a fractured elbow and fractured ribs.
The Union Cycliste Internationale said abnormalities were found in Spanish rider Cobo's biological passport from 2009-2011.
They have imposed a three-year period of ineligibility on the 38-year-old retired rider.
Cobo will be able to appeal against the decision at the Court of Arbitration for Sport.