A disappointing first half ended poorly for Henry and Monaco, as captain and star striker Radamel Falcao was forced off injured.
Thierry Henry suffered defeat in his first match as a head coach when his 10-man Monaco side slumped to a 2-1 loss at Strasbourg on Saturday to drop into the Ligue 1 relegation zone.
The principality club have failed to win in 11 games in all competitions since the opening weekend of the French top-flight season, and are only above bottom team Guingamp on goal difference.
Monaco, who were runners-up to PSG last season, are now 24 points adrift of the reigning champions after they cruised to a 5-0 thrashing of Amiens at the Parc des Princes despite resting several key players.
A dreadful error by Monaco’s third-choice goalkeeper Seydou Sy gifted Strasbourg midfielder Adrien Thomasson an early opener, and substitute Samuel Grandsir was sent off midway through the second half.
Lebo Mothiba doubled the advantage, and a late Youri Tielemans penalty was a mere consolation for the 2017 Ligue 1 title-winners.
“It wasn’t easy, we tried to put something in place which worked at the beginning, and then we conceded that goal that I don’t need to describe… Human error, I don’t want to wipe the floor with anyone,” said the 41-year-old Henry.
“Then we tried to change the game, and unfortunately Sam (Grandsir) is sent off. After that it was even harder.
“But I want to keep positive despite the negatives, otherwise you don’t move forward, and the positive thing is that we tried to keep playing, even with 10.”
Henry — a World Cup winner and Arsenal’s all-time record goalscorer who started his playing career at Monaco — made four changes to the team which lost to Rennes before the international break, with former Manchester City and Inter Milan striker Stevan Jovetic restored up front.
But his new side got off to the worst possible start as they handed Strasbourg a 17th-minute lead.
Kenny Lala’s long ball forward was nodded hopefully towards goal by Thomasson, but Senegalese ‘keeper Sy — who was only playing due to injures to Diego Benaglio and Danijel Subasic — comically fumbled the ball over his own line.
A disappointing first half ended poorly for Henry and Monaco, as captain and star striker Radamel Falcao was forced off injured.
It was proving a miserable debut for Henry, as just two minutes after being brought on as a substitute, Grandsir was given a straight red card for catching Anthony Goncalves in the hip with a high boot, with the Strasbourg winger collapsing to the ground holding his face.
As the visitors pushed for an equaliser, they were hit on the counter-attack in the 84th minute as South African international Mothiba raced clear before a cute lob gave him his seventh goal of the season for club and country.
Tielemans pulled one back with an injury-time spot-kick after Moussa Sylla was brought down in the area, but it proved too little, too late.