Favourites Argentina must turn one-man band into full orchestra

World Cup contenders Argentina arrived in Brazil with high hopes but Saturday's last-gasp win over underdogs Iran exposed deficiencies within the team that need rapid improvement if they are to mount a realistic title bid.

Lionel Messi's sumptuous stoppage-time strike may have secured a ticket through to the next round with a Group F game to spare but Argentina's attack and defense looked anything but world class against an arguably much weaker opponent.

Going into the game with one of the most intimidating attacking formations in the business, with Messi joined by Sergio Aguero, Gonzalo Higuain and Angel Di Maria, Argentina were scrappy going forward and left gaping holes in defense.

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The 'Fab Four', as the quartet is known, looked more like a hastily assembled tribute act that were completely out of tune for most of the game and their 1-0 victory was barely deserved.

Higuain and Aguero managed only one shot each in the entire game compared to Messi's six.

"We have to have a good look at what happened and try to improve. We have a few causes for concern," head coach Alejandro Sabella told reporters.

One of those areas is Argentina'a work down the flanks with Aguero and Di Maria, whose combined worth is several times more than that of the entire Iranian team, proving completely ineffective against their unheralded opponents.

"We know we are not playing as well as we are expected," Messi said. "But as we go along in the tournament, we will be improving and we will reach our full potential."

Higuain's own effectiveness as a striker was also brought into question with Sabella taking him and Aguero off late in the game in an effort to revive his front line.

Despite a crowded defense and three or even four Iranians marking Messi in midfield, the ball was circulated out to the wings far too infrequently.

Against tougher defenses later in the tournament, their work will only become that much harder.

"We did go down the one side but we did not do it that well over both wings," Sabella said.