Joey Barton was sent off for the first time this season as Marseille lost their seventh Ligue 1 match at home to Nancy.
Barton was shown two yellow cards in the space of five minutes before André Ayew scored an own goal with 17 minutes remaining at the Stade Vélodrome.
Barton was red-carded on his 14th appearance for the French side and it was his first dismissal since the final day of last season for Queens Park Rangers at Manchester City.
It was the seventh red card of Barton's career, almost nine years to the day of his first while playing for Manchester City at Tottenham in the FA Cup.
Marseille are six points behind Ligue 1 leaders Pars St. Germain.