Thierry Henry started his managerial career with Monaco on a losing note as the 2004 Champions League finalists slumped to a 2-1 defeat at Strasbourg on Saturday.
Goals from Adrien Thomasson and Lebo Mothiba ensured a losing start for Henry, who had high hopes of turning things around for the struggling side during his unveiling earlier in the week.
The defeat leaves the side in 19th spot in the Ligue 1 standings.
Monaco were forced to battle for the last 24 minutes with 10 men after the sending-off of Samuel Grandsir and Youri Tielemans scored an injury-time consolation from the penalty spot.
Henry sought to make an immediate impression with four changes for the trip to the Stade de la Meinau and they made most of the early running against their mid-table opponents.