The Portuguese captain was hampered by thigh injuries at the back-end of last season with Real Madrid and is yet to train fully after reporting for international duty.
Without their talisman on the pitch, Portugal laboured to a stalemate with the Greeks in Oeiras in both sides' final game on European soil before heading to the United States.
Ronaldo was crucial to Portugal reaching the finals, scoring all four of his nation's goals in their play-off win over Sweden.
And they face a tricky test, having been drawn against Germany, Ghana and USA in Group G for the showpiece in Brazil.
Though Bento recognises the need for his side to step up if Ronaldo is not fit, he will happily lean on the 2013 FIFA Ballon d'Or winner if need be.
"Whoever we have in the team, we'll have to compete. 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."
