Nice suffered their first Ligue 1 defeat of the season as they went down to a surprising 1-0 loss at struggling Caen.
Ivan Santini's penalty late in the first half proved the difference in an attritional affair that saw the visitors give up their six-point lead at the top of the table.
The hosts went closest to opening the scoring on the half hour when Damien Da Silva met Vincent Bessat's free-kick at the back post but his goalbound header was turned away by Yoan Cardinale.
Then, shortly before the interval, Caen were handed the perfect opportunity to gain the advantage when Ronny Rodelin was fouled by Henrique Dalbert inside the area.
Santini took charge from 12 yards and sent Cardinale the wrong way for his third goal in five league games.
Caen continued in the same vain after the break and almost doubled their lead in the 47th minute but Frederic Guilbert's point-blank header was superbly kept out by Cardinale.
Nice offered their first real effort just after the hour mark as in-form Mario Balotelli teed up Alassane Plea but his 18-yard effort ended up just the wrong side of the top-left corner.
And Balotelli went even closer minutes later when his first-time effort from Younes Belhanda's pass came back off the upright with Remy Vercoutre well beaten.