Marseille missed the chance to narrow the gap to Ligue 1 leaders Paris Saint-Germain when they slumped to a 3-1 home defeat against Nice on Sunday.
First-half goals from Sofiane Diop and Gaetan Laborde put Nice 2-0 ahead before Marseille reduced the arrears through Ruslan Malinovskyi after the break.
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A superb late strike from Billal Brahimi, however, wrapped up the points for Nice and ended the home side's nine-match unbeaten run in the league.
Marseille stayed second on 46 points from 22 games and now trail PSG by eight points before they host the capital side in the last 16 of the French Cup on Wednesday.
RC Lens are third, behind Marseille on goal difference, after a 1-1 draw at Stade Brestois, their third consecutive game without a win. Fourth-placed Monaco won 2-0 at Clermont to move to 44 points while Nice are eighth on 32 points.
At the Stade Velodrome, Nice went ahead in the 38th minute when Diop headed home after Laborde's strike had been parried into his path by Pau Lopez.
The visitors doubled their advantage one minute from the interval as Laborde slotted the ball home on the follow-up after Khephren Thuram's strike was saved by the Marseille goalkeeper.
Marseille coach Igor Tudor made changes at halftime with Dimitri Payet, who had been handed a rare start, replaced by Malinovskyi, while Vitinha came off for Alexis Sanchez.
It was Vitinha's first appearance for Marseille since he became the club's most expensive player after joining from Braga for a reported fee of €32 million ($34m) last month and it was one to forget.
Ukraine midfielder Malinovskyi had an almost immediate impact as he latched onto a cross from Jonathan Clauss on the hour.
Yet Marseille's hopes of turning things around ended in the 86th minute when Brahimi found the back of the net with a curled effort from just outside the box.