Bordeaux stay on course for treble
Champions Bordeaux, who top the Ligue 1 standings and have reached the French Cup last 16, dream of becoming the first team to win the league and both domestic Cups in the same season.
They will visit Ligue 1 rivals Lorient on February 17 for a place in the League Cup final.
Toulouse host Olympique Marseille in the other semi-final on Wednesday.
Bordeaux, who achieved the Ligue 1 and League Cup double last season, relied largely on reserves against visitors Sedan and had to wait for the 49th minute, when forward Yoan Gouffran exploited a defensive blunder to score from close range, to move in front.
Sedan were reduced to 10 men 11 minutes later when Croatian defender Ante Rozic received his marching orders for a tackle from behind on Bordeaux forward David Bellion.
The League Cup final is on March 27 at Stade de France.