St Etienne's five-match winning run in Ligue 1 came to a screeching halt after they succumbed to a 4-1 defeat at home to a Hatem Ben Arfa-inspired Nice.
The mercurial forward bagged a brace for the second game in a row - having also scored twice in Nice's 6-1 victory over Bordeaux - as second-placed St Etienne remained four points behind leaders Paris St Germain.
Vincent Koziello opened the scoring after five minutes and although that was cancelled out by Loic Perrin a quarter of an hour later, Nice regained the initiative thanks to Ben Arfa.
The former Newcastle man re-established the visitors' lead in the 39th minute and then scored a wonder goal on the stroke of half-time, dribbling past several defenders before shooting low across St Etienne goalkeeper Stephane Ruffier from a tight angle.
Ivory Coast midfielder Jean Seri rounded off the scoring in the 53rd minute and although Nampalys Mendy was dismissed just after the hour mark, Nice held on to secure their third win in a row.