Marseille's worrying five-match losing run finally came to an end at Rennes in a 1-1 draw marked by a saved penalty from Marseille captain Steve Mandanda.
With a lack of concentration in the Rennes defence Ayew struck right-footed from near the penalty spot for the Ghana striker's first goal in ten months of Ligue 1 action.
In the 73rd minute Rennes were awarded a penalty after Kassim Abdallah fouled Foued Kadir.
Oliveira stepped up to take the spot kick but his effort was denied by Marseille keeper Mandanda, much to the delight of the travelling fans.
This stalemate, after three losses in the league and two in the UEFA Champions league, lifted Marseille up to fifth, on 18 points.
Rennes are one point behind in eighth.
Marseille manager Elie Baup suggested the draw signified that his team had "character".
But he warned: "There's still lots of work to do...but this will do us good."
Asked if he was concerned after conceding an early goal he remarked: "Rennes always start at 2,000 kilometres an hour, we knew that, and had to hold on. We did well to come back at them.
"Now we've stopped the bleeding, we've got to continue with the cure."
Later, Lyon ended their five-match winless run with a 2-0 home victory over Guingamp, Reims ran out 4-2 winners over Bastia, Valenciennes came away from their trip to Ajaccio as 3-1 victors, Evian/Thonon saw off Toulouse 2-1 and Sochaux and Saint Etienne ended 0-0.
The Ligue 1 summit is occupied by defending champions Paris Saint-Germain, who moved three points clear of Monaco with a 4-0 rout of Lorient on Friday.
The result at a rain-drenched Parc des Princes extended PSG's unbeaten league run to 23 games.
"We scored goals, created lots of chances and kept the ball despite the difficult weather conditions," manager Laurent Blanc said.
"Our philosophy for the game is the same whatever team we put out. There are players who have little playing time but they always demonstrate their qualities."
Monaco have the chance to draw level with PSG on Sunday with a win at Lille.