The reigning Ligue 1 champions succumbed to a 3-1 defeat away to Stade de Reims on Friday, a result which leaves them in 16th place and eight points adrift of league leaders Marseille.
And, with their Champions League opener against Arsenal to be played in midweek, the 42-year old has expressed his concern with his side's style of play.
"We did everything not to win this game. I am very disappointed," the Frenchman told reporters after his side's loss.
"I do not usually blame my players, but what is happening at the moment is quite distressing. We need to return down to earth, to the fundamentals of football."
After previously insisting they would not be bullied against Arsenal, the former French international called for his players to improve ahead of the game.
"We must quickly wake up, or we will be in trouble on Tuesday," he added.