The 2010 champions must recover from the embarrassing 5-1 defeat to Netherlands, while the South Americans look to build on victory in their opener
As he faces questions of whether this tournament represents the end of an era, the Spain coach knows he has to do something to provide the answers, even if he won't abandon his philosophy.
"Of course there will be some changes, but I don't want to make any rash decisions," he said. "There's no need to single anybody out, we have 23 players available and we'll find the best possible solution."
Captain Iker Casillas is expected to keep his place in goal despite a performance he described as the worst of his career, especially with David De Gea ruled out for the rest of the group stage with a leg injury. Gerard Pique may not be so lucky after his horror show against the Dutch, with Javi Martinez ready to come in for a game Spain cannot afford to lose.
Del Bosque is likely to make changes in midfield as the World Cup holders look to recover from the defeat in their opening match – just as they did following their loss to Switzerland in South Africa four years ago.
Pedro’s anticipated inclusion will add some much-needed pace and energy in the final third, with David Silva the most likely casualty and Andres Iniesta likely to be moved out wide. Diego Costa could also make way for Cesc Fabregas, but the Atletico Madrid man’s physical threat could be useful against Chile’s lightweight defence.
Chile has no such selection headaches following its 3-1 victory over Australia on Friday.
Alexis Sanchez will be expected to lead the charge on the counterattack, with forward in impressive form off the back of his goal against Australia as he prepares to come up against a number of Barcelona teammates.
Arturo Vidal lasted an hour in Cuiaba on his comeback from a knee operation in May but looked some way from match fitness. Coach Jorge Sampaoli will hope that the Juventus midfielder can last longer against the holders at the Maracana, where his energy will be needed on a huge pitch.
Chile looked suspect defending crosses against Australia and there have been suggestions that Sampaoli may consider bringing in Francisco Silva at center back, but he is expected to continue with Gary Medel and Eugenio Mena as his central defensive pairing.