Marseille, who recorded their fifth consecutive clean-sheet, failed to threaten their sixth-placed hosts but proved solid enough to stay second in the standings with 58 points.
Lille, who had scored in their 10 previous games in all competitions, were left frustrated in sixth on 53 points.
"There are some nights you feel unbeatable and everything turns on your side. It was my night," Marseille captain Mandanda told French television Canal Plus.
"You have to be realistic," he said. "Although we are competitors and we want to win trophies, our goal is now to secure the second spot. We look backward rather than forward."
"We found a great Mandanda on our way tonight," he said. "When the keepers produce such a performance, it's complicated. But we also lacked a cutting edge."
"We talked a lot this week, we had dinner and watched the Champions League games together on Wednesday to settle things," captain Maxime Gonalons told reporters.
"We told ourselves a lot of things. It has helped. When it does not work, you have to find solutions. We put everything back in place."
Lyon leap-frogged neighbours Saint-Etienne, fourth with 54, level on points with Nice who beat lowly Sochaux 3-0 at home in the day's early kick-off.
The seven-times French champions took the lead after eight minutes thanks to Clement Grenier who tapped in Alexandre Lacazette's cross at the far post.
In the day's early kick-off, Nice missed several chances in the first half but were rewarded for their domination six minutes after the break thanks t
