The Real Madrid star played a large part in helping his country to Euro 2016 success in France, although he went off injured early in the final, which Eder won in extra-time with the only goal.
The Manchester United boss has backed the Ballon d’Or winner to replicate that influence in Russia.
“Portugal have an interesting squad. Without Cristiano, it would be impossible. But with him nothing is impossible,” he told ESPN Brazil.
Mourinho, meanwhile, believes that Argentina are contenders for a first crown since 1986 thanks to the individual talents of Lionel Messi.
“I believe that the Argentinian national team without Lionel Messi wouldn’t be a contender,” he said of Jorge Sampaoli’s side, who struggled to qualify for the competition, relying on a hat-trick from the Barcelona ace to see them past Ecuador 3-1 in their final qualifying match. “But with him, they’re one of the favourites.”
Looking at the favourites due to the strength of their squads, Mourinho picked out Brazil and Spain as two of his top picks for the competition.
“I like the basic structure of Brazil a great deal, their tactics and mentality,” he said. “There is a mixture between Brazilian natural talent, with a serious approach, physical, tactical.
“They are a team capable of defending well, allowing few goals, with a good support base. And then up front with Willian, Neymar, Philippe Coutinho and Gabriel Jesus … All players with outstanding qualities.
“And then we have the traditional teams of Europe, but I believe Spain are once again a real team. They were able to get together players with the same game philosophy, adapted to that playing style.
“I would say that Spain are in better condition than any other European rivals. But let’s see…”