The Real Madrid and Portugal icon believes that his nation have been handed the toughest group alongside two of the favourites, and that his Iberian neighbours will also challenge
The tournament gets underway on June 8 and the 27-year-old touted the trio of nations as the main contenders to lift the trophy.
"Spain have a good chance. Germany, Netherlands, Italy, Portugal, why not? But the first three have the great chance to win: Spain, Germany and Netherlands," Ronaldo said at a Castrol event which was attended by Goal.com.
"We don’t have a lot pressure. The pressure is for Spain, Germany, Netherlands. But not Portugal. We have to enjoy it, to do the best we can, and let’s see what is going to happen. It will be very difficult."
The prolific Real Madrid forward continued by discussing his thoughts on the tough draw his country have been handed, alongside Germany, Netherlands and Denmark in Group B.
"For me it’s the most difficult group in the Euros. It will be very tough for Portugal, but for the other teams too.
"They [Germany] are one of the best teams in the world, as are Netherlands. But I think it [progression] is possible, everything is possible in football.
"We are not scared of them, but we respect them because Germany always have strong and compact teams, and it will be tough.
"[Netherlands are] a tough team, but in another way. It will be interesting because Portugal want to play against good teams because the concentration is different when you play against other teams. They're a great team. They are special.
"We know that if we progress we could catch good teams [in the quarter-finals], but this is the most difficult group.
"Can you imagine Holland or Germany out in the group? It will be a surprise! But it can happen!"
Portugal kick off their campaign in Poland and Ukraine against Germany at Arena Lviv on June 9 and Ronaldo declared himself pleased with his nation's squad.
"We are a young group, a fantastic group, with a good and funny coach. It’s really good to be part of this national team, I really enjoy it and I love being there with them."