The pair are struggling with fitness, which could open the door for Nicolas Burdisso and Mariano Andujar to start in the Monumental
Clarin reports that the former Estudiantes man's biggest worry is between the posts. Samporia goalkeeper Romero came to the squad after two weeks of inactivity due to injury, and Mariano Andujar started during Thursday's training session. If Romero cannot prove his well-being, the Catania shot-stopper will be confirmed as No. 1 against the Chileans.
Demichelis is another headache for the coach. The Malaga defender was pencilled in to start alongside Nicolas Otamendi, but is now a doubt after a fainting incident on Wednesday. Nicolas Burdisso will start if Demichelis cannot play.
Sabella also changed his tactics during Thursday, switching his 3-5-2 scheme for 4-4-2. Angel Di Maria entered on the left, and looks set to start alongside Ever Banega, Rodrigo Brana and Jose Sosa with Javier Mascherano completing a one-match suspension.
Probable Argentina XI against Chile (4-4-2):
Romero or Andujar; Zabaleta, Otamendi, Demichelis or Burdisso, Rojo; Sosa, Brana, Banega, Di Maria; Messi, Higuain.