Tour de France champion Alberto Contador expects recent 2010 Vuelta a Espana winner Vincenzo Nibali to be one of his main rivals at next year's French classic.

The three-time Tour champion says the Italian Team Liquigas rider will be a "very tough rival" and "is without doubt a candidate for next year's Tour" alongside two-time runner-up Andy Schleck.

The 27-year-old Contador says Nibali's age - he is two years younger than the Spanish rider - made his Vuelta win even more impressive.

Contador says he'll likely race in next year's Vuelta a Espana on top of going for a fourth Tour de France title for new Team Saxo Bank-SunGard. Contador says it is too early to say if he would try for the Giro d'Italia as well.

Contador is one of only five cyclists to have won all three of cycling's Grand Tours.