Thomas Tuchel accused his expensively-assembled Paris Saint-Germain team of being "too passive" and lacking "precision and rhythm" following Friday's shock 2-1 defeat to bottom club Dijon.
It was a third defeat of the season for the reigning Ligue 1 champions who could see their lead at the top of the table cut to five points if Nantes win on the road to Bordeaux on Sundayl
A Kylian Mbappe goal gave the visitors an early lead before Mounir Chouiar levelled in the sixth minute of first-half stoppage time in the first half before Venezuelan international Jhonder Cadiz hit the winner in the 47th minute.
"We were too passive in the first half, not only in defence but also in attack because we did not play together," said Tuchel.
"We lacked precision and rhythm. It was much better in the second half because we had three shots before half time and 17 after the break. Maybe we didn't deserve to have success or luck with us today."
Despite being without the injured Neymar PSG would have been confident of extending their lead at the top against a Dijon team who had scored only six goals in 11 games before Friday's match played out in torrential rain.
Mbappe registered his fifth goal in his last seven games to give PSG a 19th-minute lead after a mix-up in the Dijon defence allowed Angel Di Maria to steal possession and feed Mbappe.
The French World Cup winner finished with a delicate chip over Dijon goalkeeper Alfred Gomis.
The game was held up for several minutes when Dijon defender Fouad Chafik suffered a nasty blow after colliding with his own goalkeeper, but the hosts went into the break on level terms thanks to Chouiar.
Chouiar hit the target after Keylor Navas could only parry Didier Ndong's cross into the French striker's path, who made no mistake in hitting the target.
Two minutes into the second period, Cadiz shrugged off the attentions of Marquinhos and Idrissa Gueye before tucking away a left foot shot between the legs of Navas in the PSG goal.
"We hate to lose," added Tuchel. "It could have been possible to win given the number of chances we created. We always say that we are in another league. We must accept defeat and improve but I retain confidence in my players."
The three points lifted Dijon into third from bottom in the Ligue 1 table while PSG will now need to regroup before facing Club Brugge in the Champions League at home on Wednesday.
