Argentina's Lionel Messi trains on his own as he recovers from back injury

Lionel Messi trained apart from his Argentina teammates on Saturday as he recovers from a back injury ahead of the Copa America.

Messi picked up the injury in a friendly against Honduras last week, but Argentina reported he had improved before he flew to Spain to complete his tax evasion trial.

He returned to the Albiceleste for a light workout on Friday night and was by himself as he took to the training field on Saturday.

The Argentine Football Association said in a statement: "Lionel Messi and Lucas Biglia trained separately, while Javier Pastore and Ezequiel Lavezzi participated in the group play with a ball and then practiced apart."

Argentina open the Copa America against Chile, their stiffest test of the group stage, on Monday in Santa Clara, California.

"We're hoping [Messi] is available for the game," coach Gerardo Martino told Chilean newspaper El Mercurio. "His presence will be decided last minute, because the lumbar region is very delicate.

"He's very eager to have a very good Copa and to win it. From the way I saw him, I shouldn't be worried."

Biglia is dealing with a muscle tear, and was even reported last week to be dropped from the squad, but the Lazio midfielder is still trying to gain fitness.

Augusto Fernandez, who is likely to replace Biglia against Chile, said the remaining players can't let the injuries affect them.

"When there's adversity the team needs to step up, and instead of worrying we need to own the adversity. If [Messi] doesn't play, we need to be able to perform the best way possible," Fernandez said.

"He's the best player in the world and we all want him there. The decision will be the best for him and his health, because we need him well."

Pastore and Lavezzi are also fighting to recover from minor muscle tears, though their prognosis is better.