Angel di Maria, who earlier hit the crossbar directly from a corner, found Neymar with a ball over the top and the Brazilian’s shot was deflected in.
Neymar also hit the post and the crossbar in the space of two minutes after scoring his goal.
Unai Emery’s side visit Champions League holders Real Madrid in the last 16 first leg on Wednesday.
arseille, who were in second place, drew 2-2 at Saint-Etienne on Friday and sit 13 points behind PSG.
Monaco beat Angers 4-0 later on Saturday to move one point above Marseille.