Marseille's players were booed by their supporters after their lacklustre showing against 15th-place Le Mans at the Stade Velodrome.
"We lost points and are left with regrets. We had the feeling we were facing a wall built by a team playing with eight defenders," Marseille coach Eric Gerets told reporters.
"We are going through a difficult evening for the second time this week but it's life and we are not dead yet," he added referring to the 1-0 defeat at home to Twente Enschede in the UEFA Cup last-32 first leg match on Thursday.
Seven-times champions Lyon have 52 points from 25 games after a solid 2-0 win at Nancy on Saturday.
Paris St Germain, who were held 0-0 at Grenoble, are second on 46 points.
Marseille are third on 45 and just ahead of Toulouse on goal difference. Fifth place Girondins Bordeaux have 44 points following a 1-1 draw at struggling side St Etienne.
Marseille had most of the possession in the first half but the best chance went to Le Mans on the half hour when Belgian striker Roland Lamah darted through the defence only to see his shot deflected wide by keeper Steve Mandanda's right foot.
In the second half, Marseille pushed hard but did not manage to bypass the sturdy Le Mans defence.
St Etienne opened the scoring in the 53rd minute through 21-year-old striker Blaise Matuidi who fired a 20-metre shot in the far corner.
Bordeaux levelled one minute from time after Fernando Cavenaghi netted following a corner.
The result leaves St Etienne in the drop zone with 25 points.
