Paris Saint-Germain suffered a shock 2-0 loss to Reims at the Parc des Princes on Wednesday with headers from Hassane Kamara and Boulaye Dia giving the visitors a famous win.
The Ligue 1 champions, depleted by a spate of injuries, remain top of the table after seven games, but have already lost twice this season after defeat at Rennes last month.
It was PSG's first home loss in the league since a 2-0 reverse at the hands of Rennes in May 2018, ending an unbeaten run of 22 matches at the Parc.
PSG only lead second-placed Angers on goal difference, after Rachid Alioui's late double grabbed Stephane Moulin's side a 2-0 win at Toulouse.
"I'm disappointed with our performance. The first 10, maybe 15, minutes went well but then every minute that passed was worse and worse," said PSG coach Thomas Tuchel.
"We did not show what we are capable of doing -- so defeat is deserved."
Neymar, who had scored late winners in each of his previous two Ligue 1 games, started alongside Eric Maxim Choupo-Moting and Pablo Sarabia up front, with Edinson Cavani, Kylian Mbappe and Mauro Icardi all still injured.
But the Brazilian, who failed to force through a return to Barcelona in the close-season, was a peripheral figure and was guilty of gifting Reims possession on numerous occasions.
Tuchel was also forced to play a makeshift midfield featuring full-back Juan Bernat, with Marco Verratti suspended.
The hosts made a slow start, despite Neymar going close with a free-kick, and fell behind just before the half-hour mark.
Reims, who also beat PSG 3-1 on the final day of last season, launched a rare attack and Hassane Kamara rose to powerfully head home Zimbabwean Marshall Munetsi's right-wing cross.
PSG's injury woes intensified further shortly before half-time as Choupo-Moting hobbled off to be replaced by Angel Di Maria, who had originally been rested and named as a substitute.
Reims came agonisingly close to doubling their advantage in first-half injury-time, as centre-back Yunis Abdelhamid's header bounced narrowly past the post.
PSG dominated possession for much of the second half without posing a serious threat, and Reims again came within centimetres of making it two as substitute Remi Oudin's low, left-footed effort struck the base of the post.
And Dia entered the fray before planting another fine header past the despairing dive of home goalkeeper Keylor Navas, sealing a richy-deserved victory.
Osimhen scores again
Earlier on Wednesday, Nigerian striker Victor Osimhen scored as Lille moved into third with a 2-0 victory over Strasbourg, while Lyon were held by Brest.
Last season's runners-up Lille have now won all four of their home league games this term and sit two points adrift of PSG.
The 20-year-old Osimhen put Christophe Galtier's Lille into a 43rd-minute lead at the Stade Pierre-Mauroy by lashing home after some slack Strasbourg defending to net his sixth goal in seven games this season.
The three points were secured 19 minutes into the second half as Osimhen turned provider for former Chelsea and Marseille forward Loic Remy to slide in his first goal of the campaign.
Elsewhere, Lyon saw their winless streak extended to six matches in all competitions with a 2-2 draw at promoted Brest.
Moussa Dembele moved joint-top of the Ligue 1 goalscoring charts on six strikes with Osimhen by giving Lyon a 28th-minute advantage, but Yoann Court equalised for Brest less than 60 seconds later.
Maxwel Cornet appeared to have eased some of the pressure on Lyon coach Sylvinho by netting in the 69th minute, but Court completed his double to snatch Brest a point with five minutes remaining.
Lyon, widely considered PSG's likeliest title challengers ahead of this season, slipped to 11th, already six points off the pace