Spain were ripped to shreds in a morale-sapping 5-1 defeat by the Netherlands in their Group B opener on Friday - their worst World Cup loss since a 6-1 mauling by Brazil in 1950.
With Chile recording a 3-1 victory over Australia in their opening match thanks to a suicidal attacking style, according to midfielder Arturo Vidal, the South Americans will reach the next round if they beat Spain and the Dutch sink the Socceroos in Wednesday's first clash.
"For them it's going to be a fight to the death," Chile forward Esteban Paredes said of Spain. "And for us it's going to be a real final, because a win will mean we are almost qualified."
The Australians are expected to provide little resistance to the Dutch in Porto Alegre (1600 GMT) before Spain look to repeat their 2010 trick of losing their opening match but going on to win the tournament.
Wednesday's matches conclude in Manaus with Cameroon and Croatia aiming to bounce back from opening Group A defeats and keep their bid for a knockout berth alive.
Lineups:
Spain: 1-Iker Casillas; 22-Cesar Azpilicueta, 15-Sergio Ramos, 4-Javi Martinez, 18-Jordi Alba; 14-Xabi Alonso, 16-Sergio Busquets, 21-David Silva, 6-Andres Iniesta; 11-Pedro, 19-Diego Costa
Substitutes: 2-Raul Albiol, 3-Gerard Pique, 5-Juanfran, 7-David Villa, 8-Xavi, 9-Fernando Torres, 10-Cesc Fabregas, 12-David De Gea, 13-Juan Mata, 17-Koke, 20-Santi Cazorla, 23-Pepe Reina
Chile: 1-Claudio Bravo; 4-Mauricio Isla, 17-Gary Medel, 18-Gonzalo Jara, 2-Eugenio Mena; 20-Charles Aranguiz, 21-Marcelo Diaz, 5-Francisco Silva, 8-Arturo Vidal; 7-Alexis Sanchez, 11-Eduardo Vargas
Substitutes: 3-Miiko Albornoz, 6-Carlos Carmona, 9-Mauricio Pinilla, 10-Jorge Valdivia, 12-Cristopher Toselli, 13-Jose Rojas, 14-Fabian Orellana, 15-Jean Beausejour, 16-Felipe Gutierrez, 19-Jose Pedro Fuenzalida, 22-Esteban Paredes, 23-Johnny Herrera
Referee: Mark Geiger (United States)