Lyon's title hopes took a serious blow on Saturday as they crashed to a 4-1 defeat at Bastia which leaves them four points back of leaders Paris Saint-Germain, who travel to Saint-Etienne on Sunday.
Bastia are now joint 13th with fellow Corsican club Ajaccio after three second half goals handed Lyon their fourth away defeat of the season.
On-loan midfielder Florian Thauvin broke open a tight first-half with a goal just before the break and although Lisandro Lopez equalised on 54 minutes, Bastia scored twice in five minutes to take command.
Former Blackburn striker Anthony Modeste restored the lead for the home side two minutes after the equaliser before Thauvin grabbed his second of the match on 61 minutes to put Bastia in control.
Remi Garde's men threw everything forward in a bid to get back in the tie but, with time running out, Tunisian international Wahbi Khazri put the icing on the cake with Bastia's fourth goal with three minutes remaining.
Third-placed Marseille struggled to a 0-0 draw at home to Ajaccio on Friday which gives PSG a chance to extend their lead to seven points if they can win at the Geoffroy-Guichard stadium in the last match of the weekend.
Playing later on Saturday, sixth-placed Lille can overtake Saint-Etienne and Nice with victory at home over lowly Evian while defending champions Montpellier, two points further back, host Troyes and can also keep alive their chances of European football next season by taking maximum points.