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Some say Lionel Messi will never be able to claim a place among the sport's greats such as Alfredo Di Stefano, Pele, Johan Cruyff and Diego Maradona, unless he wins the World Cup. But many others believe, at the age of 26 -- he turns 27 during the tournament on June 24 -- the four-time world player-of-the-year already has.

A lot will depend on how well he copes with the pressure and shrugs off an out-of-character, indifferent spell towards the end of the Spanish season.

An attack-minded Argentina generally play with Messi alongside close friend Aguero in attack and Barca teammate Javier Mascherano controlling play in the middle.

He spent a couple of months on the sidelines before returning in January and this could work in Argentina's favour as he may arrive fresher than other players.