Monaco scored a 90th-minute winner in their 1-0 triumph over Saint-Etienne to move back up to second place in the Ligue 1 standings.
Fabinho converted from the penalty spot at the end of the match to inflict back-to-back defeats on the visitors, who had previously gone 13 matches unbeaten.
The late goal could prove vital for the Red and Whites, as they were at risk of slipping out of the top three following a poor run of form.
Moussa Sylla was thwarted from his early attempt and Yuri Tielemans was the next to come close, as Monaco looked to improve on a run of four points collected from the last 12 on offer.
All of Monaco's on-target attempts came in the second half, though, with Les Verts goalkeeper Stephane Ruffier doing well to keep out Rony Lopes.
Monaco keeper Danijel Subasic was also being kept busy, however, denying Remy Cabella and Jonathan Bamba, with the latter later finding himself well positioned to block Jemerson's goal-bound effort.
Ruffier then produced two quickfire stops to keep out Thomas Lemar's free kick and Sylla's follow-up shot, but the Red and Whites managed to find a way through at the very end after Lemar was brought down by Mathieu Debuchy - Fabinho making no mistake from the resulting penalty.
MONACO (4-2-3-1): Subasic; Almamy Toure (Sidibe 68'), Glik, Jemerson, Julien Serrano; Moutinho, Fabinho; Rony Lopes (Ghezzal 68'), Tielemans (Pellegri 80'), Lemar; Moussa Sylla
SAINT-ETIENNE (5-3-2): Ruffier; Debuchy, Theophile-Catherine, Subotic, Perrin, Gabriel (Selnaes 71'); Cabella, M'Villa, Diousse (Monnet-Paquet 65'); Ntep (Hamouma 64'), Bamba
