The four-times World Player of the Year has won a glittering array of club silverware and has established himself as one of the finest footballers to grace the game, but some believe he must win the World Cup before he can be hailed as a true great.
Many others believe, at the age of 26 - he turns 27 during the tournament on June 24 - he already has.
Messi is inevitably compared with Diego Maradona, who inspired the nation to victory at the 1986 World Cup in Mexico, and will travel to Brazil with considerable expectation on his shoulders.
A lot will depend on how well he copes with the pressure and with his shrugs off an out-of-character indifferent spell towards the end of the Spanish season.
At Barcelona he was a carefree youngster who came through the youth ranks earning plenty of praise but it never went to his head. He enjoyed playing football, that was his outlet to express himself and his confidence on the pitch was in marked contrast to his generally shy personality.
Whether there were millions watching around the world, it didn't seem to matter to him as he was self-absorbed in outwitting the opposition with his trickery.
Now in his mid-twenties and a father to an infant son, he carries the responsibility of being the talisman for Barcelona and he is at a club where the fans worship him for what he has already delivered.
It is different story for the Albiceleste. During a fruitful qualifying campaign, when he netted 10 goals, Argentines warmed to him but still Messi has to measure up to Maradona.
The former Argentina captain and coach is an idol in his native country as many identify with him, the boy who emerged from the slums and restored national pride, notably with the two goals that knocked out England in the quarter-finals in Mexico in 1986.
Messi will never have that connection with the fans, having been brought up in Spain after clubs back home allowed him to slip through their fingers.
It was the Catalan side that put their faith in him as a 13-year-old and paid for him to have the growth hormone treatment that he needed to realise his full potential.
Coach Alejandro Sabella has built his side around Messi to a far greater extent than his predecessors and now at the peak of his career this could well be his best chance to emulate Maradona and bring the World Cup home.
An attack-minded Argentina generally play with Messi alongside close friend Sergio Aguero in attack and Barca team mate Javier Mascherano controlling play in the middle.
"The team is looking good and we are getting on well together but in a World Cup anything can happen, it is very difficult," Messi said in the bulld-up to gthe finals.
"The games at the World Cup are totally different. First of all the atmosphere is not like anything else. While the Champions League is great, the World Cup is special."
Messi is hoping to be 100 percent fit in Brazil having had a difficult 2013 due to a series of hamstring injuries.
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.
"Apart from the obvious down side, it was good for me physically to have a two month break," Messi said.
"I was very relaxed working at the Argentine FA facilities. Then after that I went home to Rosario and worked hard there as well, so everything was good.
"To be home with friends and family, just to be there after so much time, is good for me."