Superstar forward Neymar was sent off in the reverse fixture and started from the bench after missing training this week with gastroenteritis, while Angel Di Maria departed early through injury at the Stade Velodrome, but Marseille could not capitalise.
First-half goals from Kylian Mbappe and Mauro Icardi instead secured a commanding position against Ligue 1's crisis club, whose troubles are best illustrated by coach Andre Villas-Boas' suspension after offering his resignation.
It meant Neymar could be introduced with little risk of a repeat of the home defeat early in the season and the world's most expensive footballer duly provided a spark that pegged OM back – their frustration evident as Dimitri Payet was sent off – to secure victory and keep PSG within three points of leaders Lille.
Neymar's absence was not felt in a trademark PSG counter-attack after nine minutes when Mbappe skipped beyond Hiroki Sakai's desperate lunge and slid a cool finish under Steve Mandanda.
Di Maria appeared to hurt himself in finding Mbappe and was promptly replaced, although Neymar remained among the substitutes and some slack play at the back ensured a fizzing Pape Gueye drive had to be tipped over.
PSG was ruthless at the other end and Icardi's cute header earned a helpful touch from Alvaro Gonzalez as it looped over the static Mandanda, who might have conceded a third time before the break as Leandro Paredes thundered in an effort that kissed the outside of the post.
Marseille was better after the break and Boubacar Kamara's shot squirmed away from Sergio Rico and wide, but further chances were few and far between.
Neymar was belatedly introduced 25 minutes from time and should have immediately won a penalty, with Alvaro granted a fortunate escape following his clumsy challenge inside the area.
Marseille spent the remaining minutes on the back foot as Neymar found his groove, missing only a finish as he sought the third, before Payet's high boot on Marco Verratti was punished with a late red card.