Celtic will have to wait for their 13th title in 14 years after rock-bottom St Johnstone stunned the champions-in-waiting with a 1-0 victory at McDiarmid Park.
Away fans filled three sides of the stadium in anticipation of setting up a title party against Kilmarnock next Saturday, following yet another home implosion from Rangers, who went down 2-0 to Hibs on Saturday.
Daniels Balodis had other ideas though as the Latvian international defender bagged the only goal of the game with a terrific header from a Graham Carey free-kick, after just four minutes, which sealed a priceless three points. He had seen an even earlier chance go just over the bar, but made no mistake this time as his clever run from deep caught Celtic napping at the set-piece.
Brendan Rodgers will be scratching his head at how his charges simply didn't live up to their usual high standards, and it may have sewn some seeds of doubt, with another meeting between the two sides to come in the Scottish Cup semi-final on Easter Sunday.
Simo Valakari, meanwhile, can thank his goalkeeper Andy Fisher for this one after a stunning player-of-the-match performance throughout as Saints move to within five points of Dundee and six points of Kilmarnock and Ross County above them, with the four-way relegation dogfight set for an end-of-season showdown in the split.
Key Events
Valakari revels in Celtic scalping
Simo Valakari admitted it was great fun in the sun seeing his St Johnstone side stun Celtic.
The McDiarmid boss was beaming as his side grabbed a relegation life line after getting the better of the Hops for the first time run 32 games going back to 2016.
Daniels Balodis grabbed an early winner to cut the gap to second bottom Dundee to five points with six games to go. And Valakari is convinced the great escape is on.
What the pundits said
Brendan Rodgers will be questioning the mentality of some of his players after their shock defeat to St Johnstone.
Celtic had the chance to set up a title clinching party at home to Kilmarnock last week, but were stunned by the rock bottom Saints who took all three points thanks to Daniels Balodis' first half header.
That means the champagne is on ice for another three weeks until after the split – unless Aberdeen can do them a favour against Rangers on Sunday – with the two doing it all again at Hampden in the Scottish Cup semi-final in a fortnight's time.
But Rodgers was less than impressed with his team's inability to take the opportunity presented to them and that they only upped their intensity after falling behind to Simo Valakari's men.
And it's left question marks over some players, especially after recent defeats to Hibs and Rangers, which ocurred after similarly slow starts.
Here's what the pundits had to say about a rare Celtic defeat this season.
Raging Rodgers lets rip
Raging Brendan Rodgers warned his Celtic team they're getting too "comfortable" – and says the recent trend of starting slowly is worrying him.
The champions elect lost 1-0 to St Johnstone in Perth and it's the third time in their last six games they have dropped points.
A fuming Rodgers was in no mood to protect his stars after it as they spurned the opportunity to clinch the title at Parkhead next weekend.
Saints players speak
Andy Fisher and Daniels Balodis spoke to the Sky Sports cameras in the aftermath of this one and both were delighted with their team's performance. When asked just how big a win it was, man of the match winner Fisher replied:
Fisher: Massive. But yeah, saying that if we go into next week and lose it counts for nothing. We've got to keep our heads down, focus on the next game and make that massive win count. Hard work [was what it took to win today], the lads in front of me was excellent throughout the whole game. Yeah, can't credit them enough for that. Obviously you have to make saves in these games, and I think I did that and hopefully I can show them what I can do.
Balodis: That was a great feeling [to score], I just get a slight touch and the ball will go in. So, so happy at the start of the game. Yeah, I feel from the start of the game that I can get these balls and get one goal. That was the most important thing [to work hard and stay concentrated], no matter how, we needed three points today and the team was brilliant, everybody doing their jobs, so that is a result.
3 talking points
Saints refuse to give up. Nicolas Kuhn goes missing again. And the title party is delayed.
Plenty to unpack in our three talking points.
Full-time: St Johnstone 1-0 Celtic
It's full-time in Perth and bottom club St Johnstone have held on to beat the runaway league leaders. Daniels Balodis' first-half header was enough to give the Saints the win, thanks in no small part to an inspired performance from Andy Fisher in goal.
Celtic were well below their best and will now have to postpone their planned Parkhead title party next week.
Saints move to within five points of 11th to give their survival hopes a real shot in the arm.
Final score from Perth. St Johnstone 1-0 Celtic.
Fisher price
Adam Idah wins the header at the near post, but Andy Fisher has been a man possessed this afternoon and clutches it once more.
Another corner
Celtic are piling the pressure on and Hatate sees his cross go behind. McCowan will take.
Another corner
Celtic see their initial set-piece deflected behind and St Johnstone clear the second but the ball is right back with Celtic.
What a save
Luke McCowan is denied this time by Fisher after a great touch and shot from the Celtic sub. Pure drama in Perth.
Five minutes more
We're into five minutes of injury time here. Can Saints hold out or will Celtic find a way back into this one?
Idah fires wide
Celtic are playing it from side to side, to side and back again, and Idah is played in for a shot, but can only find the side netting.
Idah chance
Adam Idah does well down the right to outmuscle his opponent but as he looks to try and pick out a low ball across, Fisher is down well to grab it and keep a hold of it.
Yellow card for Yang
The Korean winger is cautioned for a foul on Nicky Clark after Celtic had surrendered possession.
Fisher again
Forrest plays a good give and go with Hatate, but his effort is right down the throat of Fisher, who holds on well.
Still 1-0, into the final six minutes.
What a save
Celtic have their biggest chance of the game as Idah sends a great ball across for Forrest, who diverts his close-range effort on target only for Fisher to somehow keep it out.
Wow, what a save that is. Still 1-0 Saints.
Hatate shot blocked
The midfielder does well to lead a Celtic breakout and drive goalwards, but Curtis is across well to cover.
Yang injury
Celtic have used up all their subs and one of them, Yang, has taken a knock which requires treatment in a challenge with Kimpioka.
Brendan Rodgers will be hoping he can carry on.
Kimpioka chance
Saints are nearly in here for a second as Kimpioka is presented with a chance by Trusty, but the American gets back well to make up for his error and stop the shot at source.
Griffith then sees a follow-up shot go just over the bar.
Celtic late late shows
Celtic have developed a reputation over the decades of consistently playing for 90 minutes, and loving a late goal, and it's no surprise they're top of the charts for goals in the final 15, with 22 strikes in the latter stages. Can they summon a couple here?
Celtic sub
James Forrest is on to replace Jota for the final fifteen minutes. It's Celtic's final sub.
Celtic free-kick
Mitchell is into the book after taking out Yang.
It was a terrific ball in behind for the winger, who then cut inside and was taken out.
This is in a prime position for a direct strike at goal, just outside the box enough to get it up and down.
No second half SOTs
There have been no shots on target in this second half from either side and, I say it again, that will suit the home side down to the ground.
Celtic have 20 minutes to try and salvage their next weekend title party.
Big chance
Callum McGregor's had a quiet one by his standards, but he drives forward here and slips in Yang down the right side of the box and the Korean winger sends a great low cross/shot across the face, but just wide of the post and just out of reach of the onrushing Jota.
Subs galore
Sven Sprangler, Benjamin Kimpioka, Taylor Steven and Nicky Clark are all coming on for St Johnstone here, and they'll replace Carey, Wright, Kirk and Sidibeh
Meanwhile, Luke McCowan is on for Celtic, replacing record signing Arne Engels.
Subs galore.
Saints survive
Celtic are trying to pass it in here but take too many touches and St Johnstone can clear it, with Drey Wright down and in need of treatment.
Celtic sub
Adam Idah is on for Celtic, replacing Daizen Maeda, who will not extend his consecutive scoring streak.
Hatate fires over
What a chance for Celtic as Johnston sends a great cross in from the right. It finds Jota at the back post, who does well to set it back off-balance, but Hatate blazes his effort over the bar.
That should have been the equaliser.
