Ferreira, who won 62 international caps for Portugal, heaped praise on the talismanic Juventus forward ahead of Portugal’s tournament opener against Hungary on Tuesday.
And the former Chelsea defender said his former Portugal team-mate remains one of the very best players on the planet.
“He’s one of the best in the world. In my opinion, him and Messi are the two best players in the world,” Ferreira told 101 Great Goals.
“We talk so much about Cristiano and everyone knows who he is and what he can do and how much of a top player and professional he is.
“He wants to do well in every training session, every game and every competition. Even if he loses in training, he gets so upset.
“Cristiano will be so important for us because he can decide the game at any point. The opposition have to respect him.”
Domenico Berardi puts Premier League clubs on transfer alert
Much will be placed on Ronaldo’s shoulders as Portugal look to retain the title they won four years ago.
And Ferreira said Ronaldo will surpass the French great Michel Platini’s goalscoring record at the Euros this summer as he fires the holders into the latter stages.
“I believe he will do it and it’s probably something he will have in his mind,” said Ferreira.
“He wants to be the top goal scorer for Portugal.
“He will not stop until he breaks this record, and he deserves it.”
Ronaldo may now be in the veteran stage of his career, but Ferreira said Portugal’s squad remains strong and he remains hopeful of another successful tournament for his compatriots.
“Well, it’s a different team, a few changes from 2016 but they are still a strong side,” he said.
“Obviously, we have lost Nani, Quaresma and Eder – the player who scored the goal in the final.
“But Portugal still has a good team, good players with a mix of experience and youth which is a great combination and so I believe we will have a good competition.
“I hope they can go as far as possible, but you never know what will happen in this competition.
“It’s very tricky, it all depends on how you start and obviously if the players are feeling at their best because it’s important that everyone goes in the same direction.
“I hope they can go as far as possible. I know it is difficult (to win it again), but not impossible.”