Strikes from Grant Munro, Sam Morrow and Stefan Wohlfarth helped Ross County come from two goals down to claim victory at home to Scottish Premier League leaders Celtic.
The Hoops looked to be coasting to a comfortable win as a stunning strike from Charlie Mulgrew and a Gary Hooper chip had the Parkhead side two goals up.
The home side made two changes from the line-up that drew the Highland derby at home to Inverness CT last Saturday, with Martin Scott and Stuart Kettlewell replacing Ivan Sproule and the suspended Richard Brittain.
Neil Lennon once again rang the changes from the side that fell to defeat at Juventus, with Efe Ambrose, Rami Gershon, Dylan McGeouch, Miku and Anthony Stokes coming in for Adam Matthews, Emilio Izaguirre, Victor Wanyama, Georgios Samaras and Kris Commons.
With quarter of an hour gone the visitors took the lead in somewhat bizarre fashion, after Grant Munro headed an Efe Ambrose effort out for a corner, which Mulgrew took and whipped straight over keeper Michael Fraser and into the net.
The pressure continued from the visitors, with Miku making his way through the middle of the Ross County defence, but this time Fraser was on hand to save easily.
The Hoops extended their advantage just six minutes after taking the lead, McGeouch playing the ball back to Hooper after making his way down the right allowing the English striker to finish off the move by chipping Fraser.
Just after the half-hour mark the home side did get back into the game, as Kelvin Wilson could only clear the ball into the path of Munro and the Staggies defender unleashed a strike past Forster and into the back of the net.
And with 10 minutes left in the first half Ross County got level as Iain Vigurs swung a cross in for Morrow and after his first attempt was blocked, the striker fired the ball home at the second time of asking.
On the stroke of half-time Celtic had a chance to go back into the lead, but Stokes failed to make anything of the chance as both teams went in level at the break.
Both sides had opportunities from free kicks in the opening five minutes of the second half, but Mulgrew and then Vigurs for the hosts were way off target.
Celtic almost handed Ross County the lead as Ambrose failed to clear properly, allowing Scott in on goal. But Forster came to the rescue, saving his centre-back's blushes as he came out to collect the ball.
With less than 10 minutes in the game remaining Derek Adams' side had a chance to claim all three points as substitute Wohlfarth sent an effort wide of goal.
But Wohlfarth atoned for his error in stoppage time as he got in behind the defence to head home a dramatic winner and send the crowd into raptures.
Ross County leapfrogged rivals Inverness into third place, while Celtic remain well ahead of the chasing park and are still 15 points clear of Motherwell.