Lens have 15 points but are nine behind leaders Paris Saint-Germain who have a perfect eight wins from eight.
Marseille slipped back to third, a further point adrift but with a game in hand.
Lens were 2-0 ahead inside the first 27 minutes with Florian Sotoca scoring from the penalty spot and Polish international Przemyslaw Frankowski adding the second.
In a roller-coaster first-half, Dimitri Payet then pulled Marseille level with a goal in the 33rd minute and a stoppage time penalty.
But Wesley Said settled the clash for Lens with a 71st-minute winner after being set-up by the impressive Sotoca.
The match came after a stormy week for both clubs with Lens banning some fans for 18 months after a pitch invasion against bitter rivals Lille.
Marseille supporters, meanwhile, had clashed with Angers spectators in midweek.
Wissam Ben Yedder and Kevin Volland both scored as Monaco came from behind to beat Clermont 3-1 and claim successive wins for the first time this season.
Guinea striker Mohamed Bayo notched his fourth goal this term to give top-flight newcomers Clermont an early lead, but Ben Yedder netted for the third game running to bring Monaco level on 25 minutes.
Volland, like Ben Yedder also on target in the midweek victory over Saint-Etienne, struck early in the second half before Sofiane Diop added a late third as Niko Kovac's team climbed into the top half of Ligue 1.
Monaco go to Spain next week to play Real Sociedad in the Europa League, having won their opening group match at home to Austria's Sturm Graz.
Metz earned their first victory of the campaign after overcoming fellow strugglers Brest 2-1 in Brittany.
Teenager Hugo Ekitike scored twice as a substitute to secure Reims a 3-1 win against Nantes, while Troyes drew 1-1 at home to Angers.
Mozambique international Edson Mexer snatched a late equaliser for Bordeaux in their 1-1 draw against Rennes.
PSG made it eight wins from eight on Saturday with a 2-0 victory at home to Montpellier despite the absence of Lionel Messi, sidelined by a bruised knee.