Gonzalo Higuain is training for a similar role to Lionel Messi's in the Argentina team in preparation for matches when the Barcelona forward is not playing, coach Sergio Batista said on Tuesday.

Messi is first choice as the central striker in Batista's tactics for next month's Copa America even though the coach has classic centre forwards in his squad, like Real Madrid's Higuain and Diego Milito of Inter Milan.

"The idea is to see who can take Messi's place. We have a number nine like Higuain, we're training him to be not just an area nine," Batista told a news conference at Argentina's training base outside the capital.

He won't be the same because they are (players with) different characteristics but (I want) all to know we play this way if Messi's missing," he said referring to his penchant for a possession game.

"Our idea is to maintain a game plan with four (defenders), the three in the middle and the three forwards and not change, maybe (at times) a linkman, but that's the idea without disregarding our rivals."

Argentina began preparing last week to host the tournament kicking off on July 1 when they meet Bolivia in the opening match in Group A in La Plata.

They also face Colombia and Costa Rica in their group.

Batista is sure Messi will shine in the tournament, as he did all season at Barcelona, when Argentina look to win a first major trophy since they won the Copa America in Ecuador in 1993.

"I'm confident he'll have a very good Copa America because of his desire and the commitment he has with the national team," said Batista, a World Cup winner with Argentina in 1986.

Messi has denied feeling pressure from fans to deliver the trophy and Batista said playing at home was a great opportunity for Argentina after losing the last two finals to Brazil.

"We have the obligation of winning the tournament," he said.

The South American Football Confederation announced it was extending to 23 the number of players in Copa America squads, as in FIFA's World Cup, provided they include three goalkeepers.

The permitted number has previously been 22.