Misfiring Marseille's woeful home form continued as defeat to Nice left them without a Ligue 1 victory at the Stade Velodrome since early September.
Valere Germain's clinical finish on 18 minutes, after Hatem Ben Arfa's clever ball released him, was enough to secure a 1-0 for the visitors, extending their run of just one defeat on the road all season.
Marseille had little to shout about all game and had to wait until the second half for any real efforts on goal, but Alaixys Romao could only fire over from just inside the area and Michy Batshuayi's turn and shot was easily saved by Moez Hassen.
Marseille had a decent shout for a penalty on 75 minutes when Paul Baysse appeared to handle inside the area, but, in the end, the toothless hosts did little to convince their fans.