Jordan Ayew's header in the 54th minute lifted a dominant Marseille to 15 points from five games, two ahead of Olympique Lyon who beat Ajaccio 2-0 thanks to goals in each half by Dejan Lovren and Lisandro Lopez.
Alain Traore's splendid double earned nine-man FC Lorient a 2-1 win at neighbours Stade Rennes left them third on 11 points.
"We should have been one, two or three goals ahead at halftime because we had the chances," coach Elie Baup told French channel Canal Plus.
"This is the way I want us to play."
Marseille kept creating chances after the break and Ayew eventually put them in front when he netted a powerful header from the penalty spot after his brother Andre's cross.
Second-placed Lyon struggled to create chances against Ajaccio until centre-back Lovren put them in front when he headed home Clement Grenier's corner kick in the 25th minute.
Ajaccio goalkeeper Guillermo Ochoa made two great saves after the break, parrying Grenier's fine lob and stopping a point-blank Gomis header.
"We knew it would be difficult. We tried to do our best but unfortunately, we did not get a point," Mutu told French channel Canal Plus.
"I am very confident I'll soon be in better shape."
In Rennes, Traore put the visitors ahead in the 23rd minute with a stunning shot from 30 metres and doubled his side's lead with a free-kick from the same distance minutes before half-time.
Rennes's fourth defeat of the season left them languishing in 18th place in the table.
