Marseille's miserable run continued after a goal two minutes from the end of extra-time by John-Christophe Ayina ensured Championnat side US Quevilly moved into the semi-finals of the Coupe de France with a famous victory over the Ligue 1 giants.
The match was preceded by a minute's silence to honour those killed in the shootings in Toulouse and Montauban.
Once the game was under way Marseille's shocking form, which has seen them lose five consecutive Ligue 1 games continued when they made a dreadful start with Julien Valero putting the lowly hosts ahead after just six minutes.
Marseille imposed themselves on the game more after the break, Diawara twice having headers thwarted by Quevilly goalkeeper Issa Coulibaly.
Marseille came agonisingly close when Alou Diarra's effort hit the post but with just five minutes left they levelled through substitute Loic Remy.
Rod Fanni sent in a cross which was headed on by Andre Ayew with Remy sliding home from close range.
Marseille were clear favourites going into extra-time and they missed a great chance when Jordan Ayew hit the post but it was the hosts who went ahead with nine minutes left through Ayina.
However, the lead lasted only two minutes, with Remy striking again. The game appeared to be heading for penalties before the hosts claimed a stunning victory, Ayina slotting the ball into an empty net.