Second-placed Nice suffered a shock 1-0 home defeat by Ligue 1 basement side Metz, whose flying wing-back Fabien Centonze created and finished a superb move to score the winner on Saturday.
Centonze started just inside the Nice half and, after passing the ball out wide, kept running to find the net and cap a sweeping counterattack after 31 minutes.
The defeat left Nice on 26 points, 11 behind leaders Paris Saint-Germain, who visit Saint-Etienne on Sunday, while Metz have 12.
Nice had several chances, notably near the end when Andy Delort's header went narrowly wide of the target.
Delort had also been fouled on the edge of the Metz area by Vincent Pajot at the start of the second half but, after a lengthy VAR consultation, the referee awarded a free kick rather than the penalty the home players were clamouring for.
Mario Lemina sent the resultant set piece over the bar.