In a short statement on their team website, BMC Racing confirmed Sanchez’s provisional suspension, and are now awaiting the B sample results before deciding on further action.

“All riders and staff are held to the highest ethical standard and BMC Racing Team is extremely disappointed to share this news on the eve of the Vuelta a Espana,” the statement continued.

Sanchez will now be replaced in the BMC Racing squad by Loic Vliegen, with the 23-year-old set for his Grand Tour debut as a result.

Sanchez won five stages at the Vuelta between 2005 and 2007 and is also a former stage winner and King of the Mountains at the Tour de France, alongside multiple top-ten finishes in each race.

His biggest triumph came in 2008, however, when he won the Olympic road race in Beijing, ahead of Davide Rebellin, who was later disqualified for failing a doping test, and Fabian Cancellara.

The Oviedo-born rider spent the bulk of his career, from 2000 to 2013, with Euskaltel-Euskadi before signing for BMC Racing upon the Basque team’s demise.