Bastia's midfielder Florian Thauvin bagged a brace as Lyon's Ligue 1 title hopes took a hammer blow with a 4-1 defeat at the Stade Armand Cesari.
Thauvin, who is remaining with Bastia for the rest of the season having signed for Lille in January, put the hosts in front just before half-time although Lisandro Lopez levelled in the 53rd minute.
That was as good as it got for the visitors, who fell behind almost immediately afterwards through Anthony Modeste's strike while Thauvin's second on the hour left them with a mountain to climb.
Wahbi Khazri ensured there was no way back as Lyon, who could trail Paris St Germain by seven points if the league leaders beat St Etienne on Sunday, suffered their heaviest defeat of the season.
Montpellier suffered another blow to their European aspirations as they were held to a 1-1 draw by lowly Troyes.
The home side were looking to bounce back from last week's defeat to Nice and things looked to be going their way when Gaetan Charbonnier struck early on from close range.
However, Troyes are battling for Ligue 1 survival and responded with an equalizer from Corentin Jean after the restart.
The result leaves Montpellier seventh in the table, three points shy of the top four, while second-bottom Troyes are five points from safety.
Evian's smash-and-grab raid dragged them away from danger and ended Lille's fine run of form to dent their European hopes after a 2-1 win.
Lille struck a post and missed a penalty as Evian came from behind for an unlikely win against a team who had won five games in a row.
Salomon Kalou put Lille ahead after just seven minutes, but after Dimitri Payet hit the upright, Saber Khlifa leveled on the half-hour mark, and Kalou then scored an own goal in the 67th minute before missing a spot-kick.
Lorient answered coach Christian Gourcuff's complaints about conceding late goals by scoring two early to set up a comfortable 4-0 win over Brest.
Lorient have seen their hopes of European football fade thanks to late defeats, but made sure there would be no such problems today with goals from Julien Quercia and Yann Jouffre in the opening seven minutes before further strikes from Wesley Lautoa and Gilles Sunu.
Mohamed Fofana seized his chance to give Reims a little breathing space in their battle to avoid the drop as they beat Rennes 1-0.
The Malian defender headed the only goal in the 31st minute against Rennes to make it a miserable 500th top-flight match as a manager for visiting boss Frederic Antonetti.
Antonetti is the longest serving of the current crop of Ligue 1 managers but this was not a night to remember for Rennes. Their hopes of playing in Europe next season are fading after five games without a win.
Reims, who were outside the relegation zone at the beginning of the day, moved two points clear.
Sochaux missed the chance to climb back out of the relegation zone after conceding a late equalizer at home to Valenciennes in a match they should have won.
Eric Hely's men, who dropped into the bottom three following successive defeats to last-placed Nancy and Evian, looked set to claim a morale-boosting triumph after taking an eighth-minute lead through Ryad Boudebouz and dominating for large periods.
However, after hitting the crossbar twice and also being denied by a string of fine saves by visiting goalkeeper Nicolas Penneteau, the hosts were hit by an agonizing sucker-punch with eight minutes remaining when teenage substitute Opa Nguette scored a brilliant equalizer for mid-table Valenciennes.
