Hatem Ben Arfa scored his first goal since returning to Ligue 1, but was unable to stop Nice letting a two-goal lead slip as they drew with 10-man Troyes.
Troyes took the lead within three minutes as Corentin Jean got onto the end of Mory Kone's cross before flashing his shot into the top corner of Benjamin Lecomte's net.
However, OGC were awarded a penalty within moments after Jonathan Pereira's challenge on Alassane Plea.
Ben Arfa, who was substituted against Lyon last weekend, stepped up to score his first goal since returning to France from Newcastle United.
Nice took the lead on 16 minutes as Valere Germain's cushioned header teed up Plea, who beat keeper Denis Petric low to his left-hand side.
Things got worse for AC when Chris Mavinga, once on the books of Liverpool, was sent off just after the half-hour mark after picking up a second booking for his challenge on Plea.
Les Aiglons scored a third before half time after Maxime Le Marchand powered a close-range header past Petric.
Ben Arfa appeared to be rediscovering the confidence, which led to him being capped by France and earning a transfer to the Premier League.
At one stage, the former Marseille winger used his trickery and close control to evade the attentions of four Troyes defenders, eager to regain possession, to the delight of the travelling OGC support.
He almost produced a fourth goal early in the second period as he fired wide with one shot from distance before seeing another strike blocked by the AC back line.
However, Fabien Camus set up a grandstand finish by scoring a second for Troyes and Xavier Thiago's 93rd-minute goal ensured that the newly-promoted side snatched a point.
