Inverness: Celtic's title hopes were dealt a massive blow as they crashed to a 3-2 defeat away to Inverness Caledonian Thistle on Wednesday that leaves them trailing rivals Rangers by one point with three games remaining.
Celtic kicked off knowing four wins out of four would have seen the championship return to Parkhead for the first time in three years.
But they got off to the worst possible start when Adam Rooney's flick deflected off Charlie Mulgrew for an own goal in the seventh minute.
Kris Commons equalised with a superb swerving shot just 90 seconds later but Grant Munro, who was told this week he is to leave Inverness after 13 years, restored the home side's lead in the 53rd minute.
Shane Sutherland fired Inverness further ahead in the 62nd minute before Commons pulled one back in stoppage time.
The visitors had a further penalty claim turned down a minute later as Inverness held on for a victory that hands Rangers the initiative in the race for the championship.
Celtic manager Neil Lennon said his defence had gone missing in the second-half.
"Defensively some of the guys picked today of all days to have their worst game of the season," he said.
"The penalty at the end gave us a little bit of hope but it wasn't enough. I am very disappointed with the second-half performance and it is something we have to look at for the next three games."
His Inverness counterpart Terry Butcher hailed his side's 'magnificent' effort.
"Everybody had a great spirit about them even though some have been told they have no future with the club," said Butcher, referring to the news before the match that 10 players would be leaving because of the club's financial worries.
"They are all heroes and showed great character and great heart and it was a sensational performance."
The news about the enforced redundancies didn't seem to affect the players on the pitch as the home side raced into a seventh minute lead.
Sutherland got to the by-line and drilled the ball across goal to the six-yard box where Rooney flicked the ball off Mulgrew and past Fraser Forster from four yards out.
Inverness held the advantage for just 90 seconds when a superb goal from Commons hauled Celtic level.
The Scotland star turned Ross Tokely before charging towards goal and letting fly with a left-foot screamer that took the slightest of deflections as it swerved past Ryan Esson into the net.
Almost immediately Forster came to the rescue at the other end when Rooney broke into the box but saw his shot blocked by the keeper's legs in what was a frantic start.
Inverness were appealing for a penalty in the 49th minute when Nick Ross went down under the challenge of Mulgrew but referee Mike O'Reilly waved away their protests.
However the home fans were celebrating in the 53rd minute when a sensational strike from Munro helped them regain the lead. Aaron Doran's corner was only headed as far as the centre-half who took a touch before lashing a curling half-volley past Forster.
Daryl Murphy replaced Stokes and immediately picked up a head knock which he was receiving treatment for as Inverness increased their advantage in the 62nd minute.
Lee Cox lobbed the ball into the box where Sutherland smashed an angled left-volley that struck the far post and rolled in with Forster rooted to the spot.
Forster then twice came to the rescue for Celtic, saving from Rooney who was one-on-one with the keeper before diving to stop Ross' fierce strike.
In the third minute of extra time Celtic were handed a lifeline when they were awarded a penalty after Tokely brought down Shaun Maloney which Commons dispatched expertly into the bottom corner.