Here is what we know from the few details given by Messi's spokespeople as well as media reports and local people.
Here is what we know from the few details given by Messi's spokespeople as well as media reports and local people close to the event in his home city of Rosario.
Pop star Shakira and her husband, Messi's teammate Gerard Pique, are expected among the 260 guests.
They will join old friends of the couple and footballers such as his Barcelona strike partners Luis Suarez and Neymar.
Brunette bride Roccuzzo, 29, will wear a dress by Spanish designer Rosa Clara, which has been flown over from Barcelona.
The designer has dressed stars such as actresses Eva Longoria and Sofia Vergara as well as Spain's Queen Letizia.
From 2200 GMT the guests will pack into the Hotel City Center-Casino in Rosario, near to a crime-ridden slum run by drug gangs.
The civil wedding ceremony and party will all take place inside the venue, and the guests will be lodged there too.
Messi, 30, has reportedly asked chefs to cook local delicacies such as "locro" stew and "empanada" pasties for the feast.
The star dish is a typical Argentine beef roast including chitterlings, gizzards and kidneys.
Uruguayan pop bands Rombai and Marama plus singer Karina, wife of Argentina footballer Sergio Aguero, will perform at the dance.
It is not known whether the guests will also get a song from Shakira, the Colombian diva famous for "Whenever, Wherever."
Security will be handled by a private team of Israeli specialists used by Messi for all his excursions.
Some 155 journalists have been accredited to cover the bash, but have been warned they will have no access to the guests.