Ramos made it 2–0, but Danilo had time to go against his own crossbar late on.
Marseille can rejoin Lens with a win at Lorient on Sunday and get back within six points of PSG.
Earlier, bottom side Angers claimed their first Ligue 1 win since September as they beat European hopefuls Lille 1-0.
Substitute Halid Sabanović scrambled in the only goal of the match with six minutes remaining as Angers ended a run of 21 matches without a win.
This means they will not match the French top-flight record for most games without victory in a single season – the record is held by Arles-Avignon, who went 23 matches without victory in 2010/11.
Yet they are seven points off the bottom of the table and 12th away from safety with only eight games remaining.