Barca's faith in their ability to groom the little lad from Rosario for their first team and transform him into the world's best player has paid off handsomely while River have been left to rue not making him theirs.
Messi has already won 18 titles in his eight seasons in the Barca first team - three Champions Leagues, five La Ligas, one Copa del Rey, two European Super Cups, five Spanish Super Cups and two Club World Cups.
Three World Player of the Year awards in a row look like being followed by a fourth for 2012 - and it is only March.
The Catalan club are through to the last eight of this season's Champions League and will play the Copa final against Athletic Bilbao in May though they are five points behind Real Madrid in La Liga with 10 matches left.
Messi was once again at his majestic best on Tuesday and scored a sublime hat-trick in Barcelona's 5-3 league win over Granada at the Nou Camp to cruise past Cesar Rodriguez on the club's all-time scoring list.
The diminutive forward, who has now netted 34 league goals and 54 in all competitions this season, needed 314 games to break the record, while Cesar scored his 232 goals in 354 official matches.
"He (Messi) is sat at the same table as the best in history because he was won very important titles, because he has three Ballon d'Or awards and he will be the one who wins the most because being the player he is he can achieve a lot more," Johan Cruyff was quoted as saying in the Barca's latest club magazine.
"Messi is by far the best player in the world," added the Dutchman, who won European titles with Barcelona as a player and coach and three World Player awards. "He is incomparable, he plays in a different league."
Yet winning over fans in his home country has been harder work for Messi than his exploits for his club, where he is almost never questioned except perhaps on the increasingly rare occasions when he fails to find the net.
Messi went more than 30 months between March 2009 and October 2011 without a goal for Argentina in a competitive international but the men blamed for this are national coaches unable to build a team around him.
If you can do that, like Carlos Bilardo did with Maradona in 1986, you can win the World Cup, Messi's goal in two years' time in Brazil, land of Argentina's great rivals, following the disappointments of 2006 in Germany and 2010 in South Africa.
Nester Pekerman's decision at the World Cup in 2006 not to send on a teenage Messi towards the end of the 1-1 draw against Germany in the quarter-finals that Argentina lost on penalties is a question Argentines have always sought answers for.
When Messi, now a more mature and rounded player, struggled to make headway against Germany during a 4-0 defeat at the same stage in Johannesburg in 2010, the question for coach Maradona was why he never sent Juan Sebastian Veron on to support him.
In the 21st century it is going to be harder than ever for one player to dominate the World Cup like Pele did from 1958 to 1970 and Maradona in 1986.
But Messi is on course to emulate his Argentine predecessor Alfredo di Stefano, a five times European Cup winner with Real Madrid and double Ballon d'Or winner in the late 1950s and early 1960s, in the Champions League.
Top South Americans have always shone in Europe's elite cup competition and Messi displayed his pedigree by becoming the first player to score five goals in one Champions League match in the 7-1 demolition of Bayer Leverkusen this month.
If Messi was once seen as a cross between Maradona and Italian-Argentine Sivori it is because he has the ball tied to his left foot like Maradona and the brilliance in front of goal of Sivori, Ballon d'Or winner in 1961 with Juventus.
The fleet-footed Messi is a master of timing in his finishing, picking just the right moment to steer the ball under or round the goalkeeper or chip it over a defender leaving his opponents flat-footed as he makes it all look so simple.
These are skills first learnt playing with boys bigger and older than himself in his birth town of Rosario in Argentina before hormone treatment in Barcelona beefed the little genius up to his still small, yet amazingly robust, stature.
"When he came to train with the first team when he was still very young I already noticed that he was different and that with time he would become a big star," Ronaldinho, another former Ballon d'Or winner, told the Barca magazine.
"If he carries on the way he is going he could be the best player in history."