Paris Saint-Germain saw their eight-game win streak in Ligue 1 come crashing to a halt after a shock 2-0 defeat at Rennes.
Despite star trio Lionel Messi, Neymark and Kylian Mbappe all starting, PSG's 100 per cent record was ended by goals from Gaetan Laborde and Flavian Tait either side of half-time.
It came just five days after their impressive Champions League win over Manchester City when Messi opened his goalscoring account at the French club.
But it was back down to earth with a heavy bump for Mauricio Pochettino's side after what had been a hugely positive start to the domestic campaign.
"In general, I'm satisfied, we created a lot of chances. Rennes scored with their first and the goal had a big emotional impact," said Pochettino.
"I don't like to lose, there's a bit of anger. To go 2-0 down after a good period ... We're disappointed not to have finished off what we had. It leaves us a bit bitter and disappointed."
PSG had their chances, though, particularly in the first half when both Neymar and Mbappe wasted golden opportunities to open the scoring when they failed to even trouble goalkeeper Romain Salin with a shot on target.
Messi, who was pulling all the strings for PSG, came within inches of making it 1-0 when his curling free-kick from outside the area hit the underside of the bar and bounced away to safety.
It looked like being the only moment of real quality in the first 45 minutes until Rennes, who had less than 72 hours to recuperate after beating Vitesse Arnhem in the Europa League on Thursday, scored against the run of play just before the break.
And it was some finish by Laborde who grabbed his sixth goal of the season with a brilliant first-time volley at the back post following Kamaldeen Sulemana's inch-perfect cross.
Straight after half-time, it was 2-0 when Laborde turned provider with a cross that midfielder Tait fired home to leave PSG with a mountain to climb. It was one they never really looked like overcoming.
Mbappe thought he had given his team a lifeline when finishing a move involving Messi and Angel Di Maria. But the goal was ruled out after a video review showed the French striker had been caught offside earlier in the move.
Messi also went close again when another free-kick sailed just wide of the target.
It was nearly 3-0 late on when Laborde won a penalty after going down in the box following what looked like a high boot from Achraf Hakimi.
But, after checking the pitchside monitor, referee Ruddy Buquet rightly decided Laborde had ducked down into the challenge and had been hit by the ball rather than Hakimi's boot.
PSG, beaten in the pre-season Trophy of champions by Lille, remain top of the table with 24 points, six ahead of second-placed RC Lens who beat Stade de Reims 2-0 on Friday. Rennes moved up to seventh on 12 points.