Paris St Germain's Ligue 1 title celebrations were delayed again when they suffered an embarrassing 5-1 defeat by second-placed Lille after being reduced to 10 men on Sunday.
The hosts made the most of their superiority after halftime with goals by Nicolas Pepe, Jonathan Bamba, Gabriel Magalhaes and Jose Fonte, reducing the gap with the leaders to 17 points with six games remaining.
PSG, who already missed out on the opportunity of an early celebration when they drew at home to Racing Strasbourg last Sunday, will bag the title if they win their game in hand at Nantes on Wednesday.
It was PSG's heaviest league defeat since Qatar Sports Investment (QSI) took over the club in 2011.
The game got off to an eventful start with Kylian Mbappe having two goals disallowed for offside in the first 15 minutes and PSG losing Thiago Silva to a muscle injury two weeks before the French Cup final against Stade Rennes.
Lille went ahead after Meunier diverted a Jonathan Ikone cross into his own goal in the seventh minute.
Four minutes later, Bernat volleyed home from Mbappe's cross to equalise.
However, the Spanish full-back was shown a straight red card shortly before the break when he brought down Pepe as the striker was rushing towards goal.
Christophe Galtier's side went 2-1 up six minutes into the second half when Pepe beat the offside trap to score from close range.
Mbappe tormented the Lille defence but he was isolated up front and it was Lille who scored another, in the 65th when Bamba out-paced the defence and beat goalkeeper Alphonse Areola.
Magalhaes and Fonte sealed an emphatic win for Lille with a header each in the 72nd and 84th minutes, respectively.
After the match, Mbappe, speaking with Canal+, admitted PSG's biggest failing on the night was a lack of personality.
"You can lose, but you must lose in a certain manner -- we cannot lack character like we did here," said the France international. "Shipping three, four or five goals is not normal.
"That said, losses happen, but we must play with more personality -- it is one of our biggest failings. We played like beginners here."
PSG boss Thomas Tuchel called the heavy loss "normal" before complaining about the lack of healthy players at his disposal.
"Of course, losing to 5-1 was normal, given the circumstances," said Tuchel. "What has not been normal has been winning most matches with so few players.
"We are missing too many players, and nobody is speaking about it. We lost Lassana Diarra and Adrien Rabiot, while Neymar, Edinson Cavani, Angel Di Maria, Marquinhos and Thiago Silva have missed weeks at a time. Now Thomas Meunier is down.
"Nobody is saying anything about this, though, as we keep winning. People think that playing Juan Bernat as a No. 10 is normal and players who are sick and should not play have to play anyway.
"Yes, I will be telling the president as this situation is not good."
Earlier, St Etienne moved up to fourth when Mathieu Debuchy's double helped them thrash Girondins de Bordeaux 3-0 at home.
St Etienne have 53 points, three behind third-placed Olympique Lyonnais, who occupy the final Champions League qualifying spot.
Reuters and ESPN FC PSG correspondent Jonathan Johnson contributed to this report.