Stade de Reims 3 - 1 Paris Saint-Germain
Abdul Rahman Baba, Mathieu Cafaro and Pablo Chavarría scored for Reims as they claimed a famous scalp and celebrated with their fans in a crowd of more than 20,000 in Champagne country. David Guion's side have been a fantastic addition to the top flight after coming up as second-tier champions, and they finish in eighth place, their first top-half finish in the elite since 1976.
They were well worth this victory, and have now beaten Olympique Lyonnais, Olympique de Marseille and PSG in front of their own fans this season, while also holding LOSC.
For PSG - who were again without the suspended Neymar Jr - it is a fourth defeat in their last five away league matches in what has been a torrid end to the campaign. So much of the shine has been taken off their title triumph, and all eyes here at kick-off were on Mbappé after the superstar forward stole the headlines with his comments during his victory speech at last week's Trophées UNFP awards ceremony.
The 20-year-old still had one big objective in this game - he needed four goals here to equal Lionel Messi on 36 league goals this season in the race for the European Golden Shoe award. It was not to be.
Baba breaks duck
Mbappé looked lively on the left wing in the early stages but, with the pressure firmly off them, Reims slowly grew into this game and began to threaten at the other end. Rémi Oudin forced a good save from Gianluigi Buffon after plucking a high ball out of the air midway through the first half, with the impressive Moussa Doumbia then clipping the top of the bar moments later after Marco Verratti had played his way into trouble on the edge of his own box.
Buffon also had to save from an awkward Hassane Kamara strike before the half-hour mark, but Reims got the goal they deserved in the 36th minute. Tristan Dingomé found Oudin and he picked out Abdul Rahman Baba steaming forward from left-back - the Ghanaian got in behind the Paris defence as he made his way into the box and beat Buffon from a tight angle to find the far corner and score his first Ligue 1 Conforama goal.
Cafaro sucker punch
The visitors came out in search of an equaliser after the restart but were hit by a sucker punch in the 56th minute, Cafaro's low strike proving powerful enough to beat Buffon and find the net. The veteran Italian goalkeeper got a touch to the ball but could only help it on its way in off the post.
PSG's response was rapid, as Ángel Di María's cross was headed down by Edinson Cavani and Mbappé prodded home from close range. They then applied sustained pressure to the Reims defence as they sought an equaliser, but the hosts held firm and sealed the win deep in injury time.
Baba's long clearance turned into an assist for Chavarría, with the Argentine substitute left alone to round Buffon and tuck in the third goal as every PSG outfield player had gone upfield. It was the perfect way for Chavarría to finish up - he is expected to leave the club in the close season.
THE PLAYER: Kylian Mbappé
Mbappé drew the focus onto himself even more with his comments in the last week. Starting in a left-wing role here, he could not make the difference for Thomas Tuchel's team, although he did try and he got his team's goal to end on 33 for the league campaign.
THE STAT: 38
PSG are the first team ever to score in all 38 matches in a Ligue 1 campaign.