Paris Saint-Germain warmed up for next week's Champions League meeting with Real Madrid with a dismal 1-0 loss at Nice.
PSG's lead at the top of Ligue 1 has been cut to 13 points, with Saturday's hosts leapfrogging Marseille into second place.
Keylor Navas was called into action with under a minute gone, getting himself down low to claw Amine Gouiri's shot away at the near post.
The 22-year-old came close to finding the net soon after. Khephren Thuram robbed Angel Di Maria of the ball and drove at the heart of PSG, teeing Gouiri up but his shot sailed just the wrong side of the post.
PSG's first big chance of the game followed when Neymar played one over the top for Di Maria to chase, but he couldn't get enough lift on his shot to beat Walter Benitez.
Abdou Diallo glanced over a header at the end of a timid first half for PSG, who finished the opening 45 minutes with just three shots to show for themselves.
The first half-decent chance of the second half came midway into the latter 45, with Gouiri's shot deflecting wide - believe me, neither side looked particularly bothered about trying their hardest to win this game.
Lionel Messi picked out Mauro Icardi with a wonderfully curved ball around the back of the Nice defence, but his effort too trickled wide courtesy of a deflection.
With the clock running down, Marco Verratti lost the ball in midfield and Nice stormed forward on the counter, eventually culminating with Navas denying Justin Kluivert from close range.
And on the verge of stoppage time, Nice found a winner as Calvin Stengs crossed for Andy Delort to smash into the roof of the net.
The hosts were awarded a penalty deep into stoppage time after Icardi clattered into Jordan Lotomba, but the decision was corrected to a free-kick after a VAR check as the challenge came outside the box.
Nice held on regardless to secure a famous win and boost their Champions League credentials.
Paris Saint-Germain player ratings
1. Goalkeeper & defenders
Keylor Navas (GK) - 7/10 - Kept Nice out aplenty and continues to provide top competition for Gianluigi Donnarumma.
Thilo Kehrer (RB) - 5/10 - Recovered well following a testing opening period.
Marquinhos (CB) - 6/10 - As reliable and dominant at the back as always.
Abdou Diallo (CB) - 5/10 - His long range passing helped PSG progress the ball up the pitch.
Juan Bernat (LB) - 3/10 - Poor going both ways and you can see why he was omitted from PSG's Champions League squad.
Danilo (CM) - 4/10 - Broke play up well but that was about it.
Georginio Wijnaldum (CM) - 2/10 - Completely anonymous. Barely even noticed he was playing.
Marco Verratti (CM) - 5/10 - Technically tidy without providing penetration.
Angel Di Maria (RF) - 4/10 - Very poor but at least he tried hard.
Lionel Messi (CF) - 3/10 - Some nice flashes of brilliance when he had the ball, but that wasn't often and he didn't exactly bust a gut to get on it more.
Neymar (LF) - 2/10 - Lost the ball so many times while providing a similar work ethic to Messi.
Mauro Icardi (CF, 79' for Di Maria) - 5/10
Idrissa Gueye (CM, 90' for Wijnaldum) - N/A
Julian Draxler (CM, 90' for Kehrer) - N/A