The Portuguese captain was hampered by thigh injuries towards the the end of the season with Real Madrid and is yet to train fully after reporting for international duty.
And while Bento recognises the need for his side to step up if Ronaldo is not fit, he will happily lean on the 2013 Ballon d'Or winner if need be.
"Whoever we have in the team, we'll have to compete," he told reporters. "The national team, Real Madrid or Manchester United were always stronger when they had a player with Cristiano Ronaldo's ability.
"If teams that train every day together depend on him, why should we be afraid of saying he has an enormous influence on our team?
"But we can't lose the capacity of working when he's not available for selection."
Ronaldo was crucial to his country reaching the finals, scoring eight goals in qualification and netting four in their play-off win over Sweden.
Portugal been drawn against Germany, Ghana and USA in Group G for the showpiece in Brazil.