The 29-year-old Contador, who was stripped of his 2010 Tour de France title and banned for two years after testing positive for the anabolic agent clenbuterol, is aiming for victory in the event which starts on Saturday in Pamplona, his first major race back.
But the Saxo Bank rider warned that Froome, second in the Tour de France behind Sky team mate Bradley Wiggins and also second in last year's Vuelta, could be his biggest obstacle.
"Froome could be the most dangerous because he's also a good time triallist and has a very strong team," Contador, who won the Vuelta in 2008, told reporters.
"He could have won the Vuelta last year and he was the strongest rider in the 2012 Tour de France, although it was impossible to say if he would have won it because Wiggins was very strong in the time trials."
Fourth in Holland's Eneco Tour race earlier this month, Contador said his own condition was good, but that he does not expect to make any of his characteristic dramatic moves in the first week of the race. Instead he'll concentrate on staying out of trouble.
"I'm in good shape, but often I train harder than I race. Ok, I'm more rested than other contenders, but they've got better race condition and probably they'll go better than me in the first part. It won't be my best week," the Spaniard said.
"I'm also very aware that in the Eneco Tour, there weren't any long climbs, like the ones we'll have to tackle in the Vuelta.
"Hopefully, though, I'll ride myself into top form and be in better shape than my rivals in the third week."
Contador named the three consecutive mountain top stage finishes at the end of the second week in the northern region of Asturias as the point where he expected the race to be largely decided.
"The [last climb] to the Bola del Mundo will also be important, but a lot of the race's final outcome will be as a result of what happens in the Asturian stages," he said.
"With so many summit finishes (ten in total) it will be a very different race from the Tour, in any case, very difficult to calculate and measure your strength."
Contador denied that any anger he might feel as a result of his two-year ban for doping would spur him on in the upcoming race.
"I'm in good shape, keen and motivated, even if the last two years (of suspension) have had their effect on me. I've suffered a lot.
"But thanks to the support I've received from people I've been able to overcome this situation. And now I want to do this race as well as possible, enjoy being on the bike and focus on fighting for that victory."
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