Boubacar Kamara scored the only goal of the game as Marseille saw off 10-man Bordeaux to maintain their hopes of European qualification.
Rudi Garcia's side now sit seventh in Ligue 1 as a result of the 1-0 victory at the Stade Velodrome and are just three points behind Saint-Etienne in fourth.
It was 19-year-old Kamara who settled the game with a 42nd-minute header – his first senior goal earning the hosts a vital win.
Having lost their last two outings, Lucas Ocampos had a good early chance saved before Samuel Kalu was sent off for a challenge on the Argentinian forward.
Marseille took advantage of their numerical advantage and went in ahead at the break through Kamara's header.
Morgan Sanson hit the post before the interval but Marseille failed to add to their lead – although Garcia will be pleased to get back to winning ways.