Ligue 1 wrap: Eight-goal thriller at Lorient
The hosts were in trouble at the break but were stung into after half-time thanks largely to a brace from former Arsenal striker Jeremie Aliadiere.
Strikes from Romanian international Adrian Mutu and a quick-fire double from Eduardo before half-time gave Ajaccio a handy 4-1 buffer at the main break.
But Aliadiere fired home straight after the restart and notched a second following an earlier effort that hit the post.
Alain Traore also had a goal disallowed for offside before Lorient's moment of truth came with virtually the last kick of the game.
Gilles Sunu took advantage of a nervy Ajaccio defence to turn in Ludovic Guly's inch perfect cross to complete an incredible comeback.
Bordeaux's undefeated run came to an end at 16 away to Bastia as they slumped to a 3-1 defeat.
Florian Thauvin got Bastia off to the perfect start with a pair of strikes in the first 17 minutes and the home side made sure of the points through Wahbi Khazri after Yoan Gouffran's goal for Bordeaux on the half-hour mark.
Poor weather caused the postponement of the huge clash between Marseille and Lyon at the Velodrome, which is undergoing reconstruction.
With winds gusting at up to 100km/hour and the ground encircled by cranes, match officials decided to call it off with a yet-to-be determined rescheduled date.