Marseille entered this game off the back of their first UEFA Champions League win this season and were given the opportunity to keep up their positive mood when Cedric Avinel handled the ball from Alexis Sanchez’s touch in the box.
Dimitri Payet stepped up to emphatically finish from the penalty spot on the quarter-hour mark.
Gerson came agonisingly close to sneaking through after a pass was clipped towards him, but Benjamin Leroy just about managed to hold onto the ball after closing down the Brazilian.
In the 25th minute, Bevic Moussiti-Oko drew Ajaccio level by beating Chancel Mbemba and clinically striking past Ruben Blanco from the edge of the box.
As the hosts aimed to regain the lead before halftime, Nuno Tavares danced his way into a promising position but fired into the side netting. More Marseille frustration followed just two minutes after the break, as Youssouf Kone’s cross saw Leonardo Balerdi touch the ball into his own net - helping Ajaccio to record more than one goal in a match for the first time this season.
Oumar Gonzales almost offered Marseille a return gift but was fortunate to see his unconvincing touch drift wide of the post.
Igor Tudor made a triple change shortly before the hour mark, but Les Olympiens still struggled to break down their resolute visitors as disgruntled whistles filled the Stade Velodrome.
Samuel Gigot’s inventive flick was impressively palmed away before Issa Kabore’s follow-up was blocked with 15 minutes remaining.
Bamba Dieng had three promising late opportunities but couldn’t get any of them on target as Marseille suffered their first Ligue 1 defeat of the season and only their second home league defeat since March.
Meanwhile, Ajaccio now have two wins from their last three games, having been unable to secure a victory in any of their opening seven matches this term, with the three points lifting them off the bottom of the table for now.
Flashscore Man of the Match: Bevic Moussiti-Oko (AC Ajaccio)