The former Barcelona Striker’s missed the last two games with his club Paris Saint-Germain due to knee and muscle problems. He was expected to miss Friday’s match against neighboring Uruguay but now looks fit.
“Lionel Messi is in good shape and if that continues he will play,” said Scaloni.
“In fact, he is available, when he is in good shape he knows what I think of his game and his position in the team.
“We will make a final decision this (Thursday) afternoon.”
Argentina were due to train at their home base on the outskirts of Buenos Aires on Thursday afternoon before visiting Uruguay.
When Messi was linked with his national team on Monday he was training separately but joined his teammates on Wednesday.
“It’s easy to be with Messi who always wants to play because I want him to keep playing,” said Scaloni.
Argentina sits second on the South African World Cup qualifiers, six points behind leaders Brazil but nine points ahead of Uruguay, which sits at the top of the table without qualifying matches.