Former Barcelona and Chelsea star Deco is in awe of Real Madrid star Cristiano Ronaldo's professionalism.
Deco says Ronaldo's commitment to his profession is "obsessive".
"The boy is sick, I have not seen anyone train like that, it is very difficult to be the same," said Deco to ESPN Brasil.
"Messi takes care of his body like a standard athlete, but Cristiano is incredible. It borders on the crazy because he always wants to be the best at everything and compete for everything.
"It's great to see the two players in action, but it is impossible to make a comparison."