Celtic surrendered a two-goal lead with minutes remaining to draw 3-3 with St Johnstone in a dramatic Scottish Premiership clash at McDiarmid Park.
Defender Tim Clancy gave the home side the lead in the eighth minute before Saints' top scorer Stevie May had a penalty saved by Hoops stand-in goalkeeper Lukasz Zaluska three minutes from interval after Celtic midfielder Beram Kayal had brought down Michael O'Halloran.
Kris Commons, on for Derk Boerrigter for the start of the second half, levelled from the spot in the 53rd minute with his 31st goal of the season after fellow substitute Scott Brown had been tripped by Gary McDonald.
Striker Teemu Pukki and defender Virgil van Dijk added further goals which looked to have the champions on easy street but two goals in two minutes, the first from midfielder Scott Brown in the 83rd minute and O'Halloran two minutes later, gave the William Hill Scottish Cup finalists a share of the spoils.
Saints, playing at home for the last time this season, will be delighted after fielding a much-changed side with one eye on the Cup final against Dundee United a week on Saturday.
Celtic manager Neil Lennon also rang the changes although he would not have been happy with his side's start to the game and in the way they finished.
Zaluska and forwards Pukki, Amido Balde and Boerrigter were handed rare starts for the champions who left several of their big guns on the bench including skipper Brown, Commons and Anthony Stokes.
Within 30 seconds it was O'Halloran who almost put the home side ahead, his drive from distance beating Zaluska but rebounding off the post to safety.
Top scorer May had a hand in the Saints' opener when he had an angled drive saved at the near post by Zaluska.
From the subsequent corner floated in by Lee Croft, McDiarmid Park stopper Steven Anderson's header towards the goal was redirected into the roof of the net by Clancy, standing a couple of yards out for his first goal since scoring against the Hoops for Hibernian in 2012.
Celtic responded and Perth goalkeeper Alan Mannus had to deal with a decent long-distance drive from Pukki but there was little between the teams as the first-half unfolded.
When Kayal brought down O'Halloran to stop the midfielder's mazy run just inside the box, it gave May the perfect opportunity to grab his 28th of the season but Zaluska dived low to his left to save the spot-kick.
There was still time for O'Halloran to blaze a shot over the bar after he burst through on goal.
For the start of the second half, Brown replaced Adam Matthews and Commons came on for Boerrigter, as Nigel Hasselbaink replaced May.
The Perth side started sharply again with Van Dijk moving smartly to block a shot from Lee Croft, with Saints stand-in captain Frazer Wright heading the corner past the post.
But both Celtic's interval substitutes were involved for the visitors' equaliser, Brown being tripped by McDonald in the box as he turned inside the midfielder with Commons blasting the penalty high past Mannus.
Celtic looked more energised than they had in the first period.
Worryingly for Saints with the cup final in mind Gary Miller limped off to be replaced by David Wotherspoon, but Celtic kept coming.
Their second goal came when Mannus pushed a Mikael Lustig cross the ball wide but only to left-back Charlie Mulgrew who steered the ball back into Pukki who drove it first time past the helpless Saints keeper.
Four minutes later Van Dijk rifled in number three from the edge of the box after Commons' shot had been blocked by Paddy Cregg.
It looked all over for Saints but Brown pulled a goal back in the 83rd minute with a deflected drive before O'Halloran levelled with a header two minutes later from a Wotherspoon cross to give the McDiarmid Park men a late point.