New head coach Thierry Henry saw his AS Monaco side slump to a sixth Ligue 1 defeat in 10 games as they lost 2-1 away to Strasbourg in his first game in charge on Saturday, with Samuel Grandsir sent off in the second half.
It took just 17 minutes for the hosts to go ahead after a howler from goalkeeper, Seydou Sy.
Youri Tielemans' late penalty was only a consolation, with Monaco above bottom club Guingamp on goal difference. "Human error, I don't want to wipe the floor with anyone", said the 41-year-old Henry. "I want to keep positive despite the negatives..."
But Monaco's biggest blow came in the 66th minute when Grandsir - introduced as a substitute just one minute and 51 seconds earlier - was shown a straight red card for a high foot on Anthony Goncalves. After that, it was even harder. In addition, we lost [Radamel] Falcao at the beginning.
Coach Thomas Tuchel left key men Neymar, Thiago Silva and Thomas Meunier out of the squad altogether at the Parc des Princes with Wednesday's Champions League clash with Napoli in mind, but PSG had more than enough to see off Amiens, with Mbappe scoring his 11th goal of the campaign.
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.
Monaco had a number of chances from set pieces before Strasbourg's Lebo Mothiba chipped over the advancing Sy six minutes from time.
Mothiba, fresh from global duty, was handed another start for the home side following his brace in the last league game.