Newly-promoted Strasbourg stunned Neymar's Paris Saint-Germain 2-1 on Saturday to inflict the first defeat of the season on the runaway Ligue 1 leaders.
The exhausted Strasbourg players charged over to their gobsmacked fans at the final whistle of a breathless encounter which saw the lowly hosts hold off a bombardment from their all-star guests that lasted right to the end of the nine minutes of stoppage time.
Stephane Bahoken downed PSG, who travel to Bayern Munich on Tuesday, with a bullet finish in the 65th minute to drag the lowly home side away from relegation trouble and up to 14th.
His goal also gave Marseille the chance to close the 10-point gap between Rudi Garcia's in-form side and PSG when they face Montpellier on Sunday.
"We missed out tonight. We created chances but we weren't able to convert them. We conceded two silly goals, we lacked a bit of concentration," PSG defender Marquinhos told Canal+.
"We will learn from this. We have a very important match coming up and we need to think about that already."
Striker Bahoken struck just as Unai Emery's side looked primed to snatch the three points, with Kylian Mbappe equalising Nuno Da Costa's 13th-minute headed opener three minutes before the break and PSG piling on the pressure.
But with PSG camped in Strasbourg's half and the rested Edinson Cavani readying himself to come on to push for the win, Bahoken raced onto Da Costa's flick-on and thumped his winner past Alphonse Areola to consign PSG to their first defeat in all competitions since April.
Dominant but wasteful PSG had two gilt-edged chances just before Mbappe eventually equalised, and both were fluffed by Angel Di Maria in the space of two minutes.
First the Argentine sliced wide from a tight angle in the 39th minute after racing onto Neymar's precision through-ball, then he shot straight at Bingourou Kamara when fed neatly by his countryman Javier Pastore.
Pastore thought he'd given PSG a deserved lead just before the break when he spun on Mbappe's cross and drilled a hard low shot that flashed past Kamara but crashed off the post and back into the beaten keeper's arms.
PSG continued to press for the winner throughout the second half but Bahoken struck in a lightning breakaway attack, and Strasbourg shut up shop for the final 25 minutes.
They kept the away side at bay in a frantic final flurry that saw substitute keeper Alexandre Oukidja save the points with seconds remaining, tipping away Cavani's header just as the Uruguayan looked certain to snatch what would have been a heartbreaking point.