They love their football in the French Mediterranean port city, but they always hated PSG, even before Qatar bought the capital club in 2011.
"Le Classique" -- as it is sometimes known -- is the biggest fixture in French football, and on Sunday it will have a distinctly Argentinian flavour.
This will be Sampaoli's first match against PSG as Marseille coach. In the away dugout will be his compatriot Mauricio Pochettino. In the away team will be Lionel Messi, getting his first taste of France's biggest grudge match.
Messi was the hero of so many Clasicos for Barcelona against Real Madrid and is the all-time top scorer in the history of that fixture.
He will be conspicuous by his absence when the Spanish giants go head to head on Sunday afternoon.
Instead he will take to the field at the Velodrome a few hours later, ensuring possibly greater interest globally than ever before in a Marseille-PSG game.
Table-toppers PSG are overwhelming favourites. They have lost just once to OM in 10 years.
PSG now totally dominate French football, but once Marseille were the country's pre-eminent club, and they remain the only French winners of the Champions League, in 1993.
They have a proud history, and in Sampaoli they have a man capable of giving new hope to a city obsessed with "l'OM".
"It is the kind of club I like. Clubs like Marseille and Galatasaray who have that support, the clamour of the people that means the city explodes if you win something," he once told the magazine So Foot.
Sampaoli, 61, was born in Casilda, an hour outside Messi's home city of Rosario.
Like Messi, Sampaoli played in the youth ranks at Newell's Old Boys. While Messi left for Barcelona aged 13, Sampaoli's playing career was halted by injury before it properly began.
There are parallels between Sampaoli and Marcelo Bielsa, who became a cult hero in charge of Marseille in 2014-15 and who managed Pochettino at Newell's, the pair reaching the Copa Libertadores final in 1992.
Sampaoli, like Bielsa before him, can be seen pacing nervously up and down his technical area during games at the Velodrome. In contrast Pochettino usually cuts a cooler figure.
While Messi has spent his entire career in Europe, Sampaoli made his name coaching outside Argentina and led Chile to victory in the 2015 Copa America, beating Messi's Argentina on penalties in the final.
Sampaoli then led Argentina to the 2018 World Cup in Russia, but it was a disastrous campaign.
Messi helped secure a victory over Nigeria that rescued qualification for the last 16, but there they were torn apart by Kylian Mbappe and France, and Sampaoli departed.
Now they find themselves in opposing camps in Ligue 1 after Messi's move to Paris in August.
"It is good to have Leo here. Everyone will want to watch the French league, but in reality it also creates a huge difference in power," Sampaoli said at the time.
“With the massive gulf in financial power between PSG and the rest, and with the quality of players they have, now they have added the best player in the world."
The Messi factor means the celebrations in Marseille will be quite something if they can get the better of PSG.
Pochettino, who hails from the same province of Santa Fe as Sampaoli and Messi, will have Mbappe in his line-up and will hope to have Neymar back from injury.
He may also find a place for Angel Di Maria, who started his career at Rosario Central, the city rivals of Newell's, and Mauro Icardi. Both were born in Rosario.
All of them are familiar with the passion for the game that will make Sunday at the Velodrome such a spectacle.