Barring the 2011 Tour de France, which he raced injured after crashing and badly hurting his knee on the first day, the 29-year-old has won every Grand Tour in which he has taken part since winning the Tour de France in 2007.
Victorious in two Tours de France, one Giro d'Italia and one Vuelta, Contador also won the 2010 Tour and 2011 Giro but was stripped of both titles because of a doping suspension which he completed on August 5.
Speaking at a Vuelta rest day news conference in a country hotel near the northern port of Santander, Contador said it would be "complicated" to win but added: "I can't change myself, and one thing that never crosses my mind is not to go for the overall victory."
Contador said the Vuelta's final-week route, with two summit finishes, was not the best for his plans.
"If there was a climb close to the finish on one stage where I could attack from further out rather than having to wait for the last four to five kilometres to make my move, that would be ideal.
"And we've only really had 13.5 kilometres of flat time trial but the route is what it is and we have to adapt to that."
Asked who he would bet on to win the race, Contador smiled and said: "Myself. If I didn't believe in my possibilities, then I would be deceiving myself."
The Saxo Bank-Tinkoff rider said he felt his lack of racing before the Vuelta had affected his chances. Since his ban ended, Contador has had time to take part in only one stage race, the seven-day Eneco Tour in the Low Countries, before heading to the Vuelta start in Pamplona on August 18.
"More racing would have blown away any dirt there was in the engine," he said. "I lack punch.
"If I had a little better race condition there's no doubt I wouldn't have lost time where I did in the first week.
"But Joaquim's form is impressive, too, and we have to congratulate him for that."
Contador said he would target the world championships in the Netherlands after the Vuelta, with the time trial on September 19 and the road race on September 23 in his sights, as well as cycling's last top classic of the season, La Lombarda, on October 20.