Match ends, Kilmarnock 2, Celtic 1.
Stuart Findlay's stoppage-time header earned Kilmarnock a dramatic comeback win over Premiership champions Celtic.
With 10 points from six games, Brendan Rodgers' side are enduring their worst start to a league season for 20 years.
Leigh Griffiths pounced on a miscued Greg Taylor clearance to give them a half-time lead at Rugby Park.
But Chris Burke levelled with a brilliant long-range howitzer. And Findlay planted his decisive late header into the bottom corner.
The defeat leaves Rodgers' team sixth in the table, six points adrift of league leaders Hearts.
Killie climb above Celtic into fifth courtesy of their superior goal difference.
- Celtic fans 'should be alarmed' - Rodgers
- Killie beat Celtic in thrilling finale - reaction
- How did the players rate at Rugby Park?
Killie triumph in war of attrition
This game was a battle laced with so many compelling storylines.
Against a backdrop of refereeing controversy and vehement complaints from Killie manager Steve Clarke, Dedryck Boyata brought the speeding Jordan Jones to ground as he raced towards the Celtic box early on.
The Belgian escaped with a booking, perhaps saved by the presence of the back-tracking Kieran Tierney, but the early tumult set the tone for an incident-laden contest.
At 34, Kirk Broadfoot is a vastly experienced defender, yet he looked like an ungainly rookie when defending set-pieces. Slow and cumbersome, he could have conceded a penalty after grappling with Boyata, then let the Celtic centre-back have a free run and header at a corner and was bailed out by a terrific Jamie MacDonald save.
There was Youssouf Mulumbu, making his Celtic debut against the team he helped propel to fifth place last season, rugby-tackling Aaron Tshibola after a naughty challenge. And there was the deadly Griffiths, his speed and litheness in leaping to nod home Taylor's horrible miss-kick again underlining his credentials to lead Celtic's line.
This was Killie's day, though. The longer the impotent champions laboured in their pursuit of a second goal, then a winner, the more belief grew in home ranks. Clarke's men coped ably with the power game of Mulumbu and Scott Brown in midfield and flew forward when they could.
Burke was allowed to trot towards the edge of the box before unleashing a vicious low drive to equalise. And in the dying embers, Findlay darted towards the front post and flashed the winning header back across the face of goal. An exhilarating finish to an engrossing contest.
Celtic falter again - analysis
Something is missing at Celtic. The champions' swagger is gone. The intensity and verve that characterised Rodgers' first two years at the helm has dissipated.
Ten points from a possible 18, defeats at Kilmarnock and Tynecastle and a draw at St Mirren, are not good enough. Nor is a record of one win in five away matches.
They have only scored six goals in six Premiership games, created only a handful of chances at Rugby Park, and only in their rousing Old Firm derby triumph have they looked near their best.
Celtic will almost certainly rumble their way to an eighth successive title. They might even win another treble. But at the moment, they look worryingly listless, flat, and light years from their top form.
- 27TshibolaBooked at 61mins
- 11JonesSubstituted forNdjoliat 84'minutes
- 25BrophySubstituted forMcKenzieat 90'minutes
- 19StewartSubstituted forDickerat 80'minutes
- 20BoyataBooked at 4mins
- 27MulumbuBooked at 60minsSubstituted forMcGregorat 70'minutes
- 73JohnstonSubstituted forEdouardat 79'minutes
- 11SinclairSubstituted forMorganat 65'minutes
- Craig Thomson
- Shots on Target
Second Half ends, Kilmarnock 2, Celtic 1.
Goal! Kilmarnock 2, Celtic 1. Stuart Findlay (Kilmarnock) header from the centre of the box to the bottom left corner. Assisted by Chris Burke with a cross following a corner.
Corner, Kilmarnock. Conceded by Scott Brown.
Dedryck Boyata (Celtic) wins a free kick on the left wing.
Foul by Mikael Ndjoli (Kilmarnock).
Substitution, Kilmarnock. Rory McKenzie replaces Eamonn Brophy.
Kieran Tierney (Celtic) wins a free kick in the attacking half.
Foul by Kirk Broadfoot (Kilmarnock).
Foul by Lewis Morgan (Celtic).
Chris Burke (Kilmarnock) wins a free kick on the right wing.
Corner, Celtic. Conceded by Stephen O'Donnell.
Substitution, Kilmarnock. Mikael Ndjoli replaces Jordan Jones.
Corner, Kilmarnock. Conceded by Scott Brown.
Substitution, Kilmarnock. Gary Dicker replaces Greg Stewart.
Substitution, Celtic. Odsonne Edouard replaces Michael Johnston.
Attempt missed. Michael Johnston (Celtic) left footed shot from outside the box is close, but misses to the right.
Dedryck Boyata (Celtic) wins a free kick in the attacking half.
Foul by Greg Stewart (Kilmarnock).
Lewis Morgan (Celtic) wins a free kick in the defensive half.