Lionel Messi looks likely to miss Argentina's most important match of the opening phase of the Copa America against title holders Chile at Santa Clara, California on Monday.
Messi has not trained with his team since he suffered a back injury in a warm-up friendly nine days ago, a 1-0 win over Honduras in Argentina.
The Argentina captain, four times world player of the year, has been working separately and may not even make it onto the field at Levi's Stadium, according to reports on Sunday from Argentine media covering the national team's base camp at San Jose.
His place will be taken by Nicolas Gaitan, a player who has won 13 caps in six years but who coach Gerardo Martino has identified as his best reserve for Messi without altering tactics.
A left-footer who likes playing on the right and cutting inside in attack, with his cub Benfica's best assists record in the Portuguese league, his game resembles what Messi does best for his country.
"I wouldn't risk him, I don't want to lose him in the first match," defender Marcos Rojo was quoted as saying with the team fearing an aggravation of Messi's injury could put him out for the rest of the tournament.
Chile would be expected to feel some relief at the possible absence of the world's best player but their captain and goalkeeper, Messi's Barcelona team mate Claudio Bravo, said: "I want him to play because he adds a lot to the match."
On Paper, the other Group D matches against Panama and Bolivia look easy for title favorites Argentina and Chile.
Colombia are also fretting on the possible absence of their captain James Rodriguez from their second Group A match against Paraguay at the Rose Bowl in Pasadena on Tuesday after he hurt his shoulder during the 2-0 win over hosts the United States at Santa Clara on Friday.
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