Thierry Henry's first game as a manager ended in defeat as his Monaco side were beaten 2-1 at Strasbourg in Ligue 1.
Frenchman Henry, 41, saw his side go behind when goalkeeper Seydou Sy fumbled an Adrien Thomasson header.
It got worse for the visitors when Samuel Grandsir saw red for a high foot, before Strasbourg substitute Lebo Mothiba made it two for the home side.
Youri Tielemans' late penalty was only a consolation, with Monaco above bottom club Guingamp on goal difference.
Monaco, Ligue 1 title winners in 2017 under Henry's predecessor Leonardo Jardim, who was sacked on 11 October, have failed to win in 11 games in all competitions since the opening weekend of the French top-flight season.
Their six-point tally from 10 games this season is also the club's worst start since the 1953-54 season.
The result sees Strasbourg rise to sixth in the table, with the principality side left to focus on Wednesday's Champions League group match at Club Brugge.
Former France and Arsenal star Henry, who began his playing career at Monaco and helped them win Ligue 1 in 1997, was assistant manager of Belgium before joining the eight-time French champions.