Laurent Blanc's champions, shorn of the services of talismanic striker Zlatan Ibrahimovic, were held to a 1-1 draw against Toulouse at the Stadium Municipal in a result that will have done little to quell speculation over the coach's future.
Wissam Ben Yedder's fifth league goal of the season put Toulouse ahead inside eight minutes, but Jean-Christophe Bahebeck equalised for the visitors after Aleksandar Pesic had missed a golden opportunity to put the Alain Casanova's men further ahead.
Blanc's next challenge sees him pit his wits against Luis Enrique as Barcelona visit the Parc des Princes for Tuesday's UEFA Champions League showdown.
Last season's runners-up Monaco slumped to a 1-0 home defeat against Nice in the Cote d'Azur derby, with a Carlos Eduardo free-kick stalling the principality club's mini-revival.
Monaco are lacking the star quality of last season after the departure of Colombian duo James Rodriguez and Radamel Falcao, but had won their last three matches in all competitions before Eduardo's seventh-minute effort put them to the sword at the Stade Louis II.
Meanwhile, newly promoted Metz made it three consecutive wins with a 3-0 victory over lowly Reims, Albert Cartier's men moving up to fifth place after an impressive start to life in the top flight.
They were aided by the visitors' ill-disciplined approach, which saw Chris Mavinga dismissed when Juan Falcon's goal was all that separated the sides.
Metz took full advantage with Ahmed Kashi making it 2-0 before Mads Albaeck's red card and Falcon's second goal compounded a miserable day for Reims.
Lille, who lost to Nice in their last outing, climbed into second with a 1-0 success at home against Bastia, on-loan Liverpool forward Divock Origi firing in the winner for the hosts in the 39th minute.
Goals from Djakaridja Kone and second-half substitute Cedric Barbosa gave Evian their second win of the campaign as they scrambled away from bottom place with a 2-0 triumph away at fellow strugglers Lorient, who had Walid Mesloub sent off late on.
In Saturday"s other fixture, Montpellier won 2-1 in the south of France to condemn Guingamp to their third successive loss and bottom place.