Traditionally, the race number one is given to the defending champion, but last year's winner Nairo Quintana (Movistar) will not be riding having participated in the 2017 Giro d'Italia and Tour de France. The organiser has therefore handed three-time winner Contador the number as a mark of respect.
The Spanish Trek-Segafredo rider announced on Monday that the Vuelta would be his last race, and he will retire from professional cycling immediately afterwards at the age of 34.
Vuelta race director Javier Guillén said: “That Alberto chooses Spain and La Vuelta to call it a career is a great honor for the whole organization”
“That Alberto chooses Spain and La Vuelta to call it a career is a great honor for the whole organisation. We are wholeheartedly grateful to the generosity he always demonstrated as a rider and that he shows once again with this decision.
"Alberto is – and will forever be – part of the history of cycling in our country and elsewhere.”
Contador has previously won the Vuelta on three occasions – 2008, 2012 and 2014 – but has never returned the following year as defending champion, and so this will be the first time he will wear number one at the Vuelta.
In addition to his three Vuelta victories, Contador has won the Tour de France twice (2007 and 2009) and the Giro d'Italia twice (2008 and 2015).
He is part of an elite club of just six riders who have won all three Grand Tours that comprises Contador, Vincenzo Nibali, Jacques Anquetil, Felice Gimondi, Eddy Merckx and Bernard Hinault.
Contador raced in the Tour de France in July, placing ninth overall behind winner Chris Froome (Team Sky).
Froome finished as runner-up in the Vuelta last year behind Quintana, and is the favourite to take the victory this year. However, both Froome and Contador will face stiff competition in the shape of Nibali (Bahrain-Merida), Fabio Aru (Astana), Romain Bardet (Ag2r) and Simon and Adam Yates (Orica-Scott).
It promises to be a fitting battle to see out Contador's career. Should Contador win this year's Vuelta he will join Roberto Heras in having a record four titles.
The 2017 Vuelta a España takes place between August 19 and September 10.
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