Germany are favourites after their ruthlessly efficient 7-1 demolition of hosts Brazil in the semi-final.
Yet in Messi, Argentina have one of the world's greatest current players who can turn a big game in a flash and would dearly love to bring home the World Cup for the first time since 1986 when the team was captained by Maradona.
In a mortifying twist for Brazilians whose rivalry with their South American neighbours runs deep, some 100,000 Argentines have invaded Rio de Janeiro for the final.
Some have paid $10,000 for an airline and hotel package, while others drove the 2,000 kilometres from Buenos Aires.
Argentine flags, tents and cars were dotted all around the famous Copacabana and Ipanema beaches in Rio. Many climbed up to the Christ statue, draping blue-and-white colours at the bottom.
Brazilian fans have largely thrown their lot in with Germany, hoping they can stop an Argentine win that would give them bragging rights for years. Some locals, with tickets to a game where they had dreamed of seeing Brazil lift a sixth World Cup, were instead donning Germany colours for the occasion.
"We have forgiven Germany what they did to us. In fact, we admire them because they played the Brazil way," said Rio resident Bruno Perreira, outside the 74,738-capacity Maracana wearing a Germany replica top and joking with Argentina fans.
THIRD GERMANY V ARGENTINA FINAL
It is the third World Cup final between Germany and Argentina. Argentina won 3-2 in a 1986 thriller in Mexico City, while Germany won 1-0 four years later in Rome in an awful game.
And the history does not stop there: Germany have kicked Argentina out of the last two World Cups in the quarter-finals, humiliatingly so by a 4-0 scoreline in 2010 when they cruelly exposed then coach Maradona's tactical naivety.
After an exciting tournament where attack has prevailed and goals have been flowing, the final is likely to be a more cagey affair with Germany employing numbers to annul Messi and Argentina wary of leaving the sorts of spaces that Brazil did.
Both goalkeepers, Manuel Neuer of Germany and Sergio Romero of Argentina, are in the form of their lives, while Messi, on four goals, and Thomas Mueller, on five, are both chasing the "Golden Boot" award for the leading scorer.
Colombia's James Rodriguez is ahead at the moment on six goals. All three are also among the 10 players short-listed for FIFA's "Golden Ball" award to the tournament's best player.
The prizes are to be announced after Sunday's final.
A goal-laden tournament has already produce 170 goals and could beat the all-time record of 171 set in France in 1998.
Brazil's agony at losing the semi-final so disastrously was compounded by another poor defensive display in Saturday's 3-0 defeat by the Netherlands in the third-place playoff match.
Having not lost a competitive home game since 1975, Brazil have now suffered two defeats in five days: a sad end to a tournament they entered with such confidence and high hopes.
An Argentina win on Sunday would complete their misery.