Javier Zanetti believes Lionel Messi remains the decisive factor that will make Argentina a genuine threat as they bid to retain the World Cup title this summer in North America.

The former Inter Milan and Argentina captain — who earned 125 caps for the Albiceleste across two decades — told FourFourTwo that defending the crown will be no simple task, but that Messi's presence changes everything.

"That won't be easy, although great young players are emerging," Zanetti said of Argentina's chances. "I'm convinced that with Messi, Argentina will be a major contender again for this World Cup."

The leader they still need

Zanetti was emphatic about Messi's continued importance to the squad, dismissing any suggestion that the 38-year-old has lost his edge at the highest level.

"He's fully capable of continuing as a leader — he's intelligent, he knows better than anyone what the team needs, and he's surrounded by talented players in the national team," Zanetti added.

Messi will turn 39 during Argentina's group-stage campaign, making this tournament almost certainly his sixth and final World Cup. His triumph in Qatar four years ago delivered the one major honour that had escaped him throughout a career adorned with eight Ballon d'Or awards.

Savour the moment

With Messi preparing for what is likely his farewell on the international stage, Zanetti also expressed a desire to see the Inter Miami star find joy in the experience — not merely results.

"The time has come for Messi to enjoy his football — the most important thing now is that he enjoys what he does," Zanetti said.

Should Messi lead Argentina to a second consecutive World Cup, it would cement a legacy that already stands beyond comparison in the modern game.