Mathieu Debuchy's own-goal two minutes into added time denied AS Saint-Etienne victory as ten-man Paris Saint-Germain grabbed an unexpected point with a 1-1 draw on Friday.
AS Saint-Etienne 1-1 Paris Saint-Germain
PSG knew victory at the Stade Geoffroy-Guichard followed by an AS Monaco defeat at home to FC Nantes on Saturday would mean the league title was theirs.
But the hosts, who have European ambitions after starting the game in ninth, just four points off fifth, were always going to be keen to poop the party before it had even had a chance to begin.
Rémy Cabella has been in sparkling form in recent weeks for Les Verts, who were unbeaten in nine league games before kick-off, and the on-loan Olympique de Marseille man netted his fourth goal in three league outings when Debuchy's cross ricocheted into his path inside the box (17').
Romain Hamouma would have doubled the hosts' lead but for Alphonse Areola in the visitors' goal (22') and the PSG 'keeper was tested again within a minute by Kevin Monnet-Paquet (23') as Saint-Etienne, now under the stewardship of former PSG assistant coach Jean-Louis Gasset, pressed hard.
Cabella should have doubled Saint-Etienne's lead when Presnel Kimpembe gave away a penalty with a foul on Hamouma (29') but Areola halted the spot-kick. Kimpembe was then dismissed shortly afterwards for a second yellow card (41') to leave PSG with a even bigger problem.
With their backs to the wall, the Coupe de la Ligue winners rode their luck. Jonathan Bamba fired over (62') and Oussama Tannane brought another stop from Areola (74') as the league leaders rocked on the ropes.
With time running out, PSG became a little more adventurous. Stéphane Ruffier was called on to push out Kylian Mbappé's low drive (77') and then brilliantly turned away a point-blank Edinson Cavani effort (90+1').
The former Monaco man must have thought he had done enough to win his team the game and claim three points that would have taken them into the thick of the hunt for a sixth-placed finish and a UEFA Europa League qualifying place.
But in a final throw of the dice, PSG surged forward when Tannane surrendered possession, Mbappé flicked on when the cross came into the penalty area and Debuchy was in the wrong place at the wrong time, the ball ricocheting off the unfortunate France international defender and past Ruffier (90+2').
THE PLAYER: Alphonse Areola
The PSG goalkeeper has had his critics in recent weeks, but was there when his side needed him in Saint-Etienne. Without his saves, Emery's men would have been returning home empty-handed.
THE STAT: 1
PSG had just one shot in the first half, their joint-lowest tally this season, matching their total in the opening period when they met Saint-Etienne back in August.