Italian title holders Inter Milan host European champions United at the Giuseppe Meazza on Tuesday evening in the first leg of their last-16 UEFA Champions League meeting.
Sir Alex Ferguson's United travel to Milan as favourites and Ronaldo is expected to be a key figure for the Premier League leaders as they attempt to secure an advantage ahead of the second leg at Old Trafford on 11th March.
But Inter captain Zanetti insists he and his team-mates are well aware that United possess a number of players who are capable of ending plans for a first European Cup since 1965.
Wolrdwide"Cristiano Ronaldo is a worldwide star without doubt, but we are not obsessed by the Portuguese," Zanetti told skysports.com.
"The danger of United is in the squad as a whole and not only one player."
But Zanetti has reiterated his confidence that perennial Champions League underachievers Inter will demonstrate they are a global force when tackling United.
"We are convinced that Inter are one of the best clubs in the world and that it is neccesary to demonstrate our ability against United," he added.
"For me, we are favourites in every game we play, but we respect United and know it is neccesary to play at 150 per cent in order to win."