Argentina have not ruled out Sergio Aguero for the remainder of the World Cup.
The Manchester City striker will, however, miss Tuesday's round of 16 match against Switzerland with a muscular injury in his left leg.
Aguero was subsituted after 37 minutes during Wednesday's 3-2 triumph over Nigeria.
Tests done on Thursday revealed the 26-year-old's problem.
"It's a first-degree muscle strain in his femoral biceps," Argentina team doctor Daniel Martinez said in Thursday's press conference. "It's a degree lower within the muscular injuries.
"He will try to recover as soon as possible."
Martinez did not offer an opinion on whether Aguero would return and play in the quarter-final, if Argentina make it to the last eight.
"We have several (treatment) alternatives that we will evaluate regarding how it develops," he said. "We have all the available resources in order to get Sergio fit as soon as possible.
"The recovery already started on Wednesday.
"From Switzerland onwards, it will depend on whether Argentina remains in the competition and on his day-to-day recovery in order to see him back on the pitch."