The European and world champions were thumped 5-1 by Netherlands in their first match of the competition, making the clash with Chile a key fixture.
"We will do what is best for the team. Nobody should be alarmed by the changes we make. The team comes before the system," Del Bosque told reporters at a press conference.
"There might be two or three changes. This is the situation we're in and we can manage it. We're flexible but we can keep some things.
"We have a squad of 23 and they're all in good condition. We had a great first half against Holland and a terrible second. We were down but there's no problem with desire. That's football. We have to come back and we have the opportunity."
Spain have won each of their last three major tournaments.