Sabella: I had to pick Demichelis
The Manchester City centre-back's inclusion in the 30-man line-up was a surprise as Argentina prepare to face Bosnia-Herzegovina, Iran and Nigeria in Group F.
Sabella insisted that he had to include the 33-year-old, even if the 37-cap defender fails to make the final 23.
"He had a great season in a football (league) that is extremely difficult, competitive and physical," Sabella said.
"He responded very well, I could not afford to leave him out of the 30 and then we'll see.
"He is a wonderful person, he knows he has a chance to make the 23, why not? We have one week to make a final evaluation."
Sabella revealed that he would make some cuts to his squad on Wednesday, but just how many remains to be seen.
Fernando Gago and Augusto Fernandez are among those carrying injuries.
"We are going to train with less than 30 and more than 23," Sabella added.
"After that we will see, but those who do not start training will not be ruled out."