The Katusha rider believes any of the trio could take the yellow jersey in Paris next month and thinks the latter stages will be decisive.
Rodriguez was originally not going to be involved in the Grand Tour event with his attentions focused on the Giro d'Italia and Vuelta a Espana, but a crash in the Giro changed his plans and he is part of their team.
"I'd put (my money) on Nibali (Astana), Contador (Tinkoff-Saxo) and Froome (Team Sky)," he told Cycling News. "I think it's going to be a very open race until at least the second week."
Rodriguez's injuries in Italy have taken their time to heal, which the Spaniard knows will stop him being a contender, but he intends to support whoever is named lead Katusha rider.
"I'll be ok for the Tour," he added. "But whilst the injuries I got at the Giro are completely cured now, the healing process took a long time.
"My form is really uneven as a result and we'll have to see how I get on when I get to the race.
"It's not going to be straightforward, but my objectives remain the same: support the team leader, and a strong ride in the mountains.
"I'm going to be building towards the Vuelta, as well, because that is and was my main objective of the second half of the 2014 season.
"I want to be at 100%. With so many climbs on the route this year it should suit me well."