© Getty Images
Bastia's Sio appeared threatening in the opening minutes of the game and he tested Mouez Hassen with a driven shot down towards the bottom-right corner.
Their lead was not to last more than eight minutes, however, as Bastia's Gillet restored parity with a headed finish from a free kick.
Bastia made them pay after half time as they took the lead through Sio, who provided the finish after a perfectly-executed counter-attack led by Floyd Ayite.
The hosts might have made the last 15 minutes a little less stressful had Junior Tallo been a little more accurate with a header.
Ghislain Printant's side were afforded a rather easy route to the victory in the closing minutes as the visitors lost another of their players, with Souleymane Diawara this time dismissed for fighting.