Quintana, who finished second behind Froome in 2013 and 2015, and third in 2016, said that the Brit was still the favourite to take yellow even if other riders were riding well.
"To me Froome still looks like the big favourite," the Movistar rider said just over a week before the race starts in Düsseldorf on July 1.
"He always approaches the Tour perfectly, it’s a race he’s been brilliant at in the past, and I’m sure he’ll be at 100% condition in July. "
Watch: Tour de France contenders - Nairo Quintana
The Colombian picked out Richie Porte as the main challenger to Froome, but said that there were a number of riders who could pose a threat.
"We've all seen Porte riding strong for the past few years, and he’s shown great abilities that make him a strong contender. Then there’s Alberto Contador and Romain Bardet, two riders with different skills, but both dangerous. Also the Orica-Scott riders, with Simon Yates and Esteban Chaves; the Astana duo, with Fabio Aru and Jakob Fuglsang, who seem to be getting to the start in great form.
As for his own chances, Quintana said that he was feeling strong on a recent trip to the Alps to recce a few key climbs, but admitted that he was taking a step into the unknown with racing the Tour off the back of the Giro for the first time in his career.
"I’m feeling good on the bike so far this month. I should be getting stronger in the next few days and reach the start in the best possible condition.
"But you can only see where you stand when you’re into the race. Everything has been different for me this season. It’s true that I’ve ridden two Grand Tours several times already in my career, but this Giro-Tour double is quite different to anything I’ve done in the past."
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