Leonardo Jardim will take charge again on Sunday, just three months after he was replaced by Thierry Henry who was himself sacked on Friday.
The club from the principality are one from bottom of Ligue 1 and desperately wanted points at the side immediately above them in the table.
But they were no match for a team that had won only once in their previous 17 league games.
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South Korean Changhoon Kwon put the home side ahead after 24 minutes with his first league goal of the season and Monaco’s task grew even harder after centre back Naldo was shown a straight red on the hour mark for a bad tackle.
Naim Sliti then doubled Dijon’s lead nine minutes later to seal the points.
The result takes Dijon on to 20 points, five ahead of Monaco, who are a point above bottom club Guingamp, who lost 1-0 at home to Stade de Reims.
Strasbourg, who got a 90th-minute goal to beat Bordeaux 1-0, are in fifth, while Nice, who beat Olympique de Nimes 2-0, are sixth.
Paris St-Germain lead the table by 10 points from Lille, with three games in hand on their nearest rivals.
(Reporting by Andrew Downie; editing by Tony Lawrence)
