Stuart Findlay scored a dramatic injury-time header as Kilmarnock claimed a famous 2-1 victory over Celtic, who have made the worst start to a Ladbrokes Premiership season for 20 years.
Leigh Griffiths headed home to put the Hoops in charge after 34 minutes, but they lost further ground on leaders Hearts after Killie upset the odds at Rugby Park.
Chris Burke equalised with a long-range drive in the 64th minute and the midfielder had a helping hand in Killie's stunning winner, sending in a corner to the far post that Findlay was able to convert.
The 10 points Celtic have taken in their first six games represents their lowest haul since the 1998-99 campaign under Jozef Venglos.
And the defending champions, chasing an eighth successive title, now lie six points adrift of Hearts, who defeated Brendan Rodgers' men at Tynecastle in August.
Old Firm rivals Rangers are up to second in the standings after thrashing St Johnstone 5-1 at Ibrox.
James Tavernier opened the scoring in the ninth minute with his free-kick on the edge of the box before Alfredo Morelos cut in from the right to smash past Zander Clark after the half hour.
Scott Arfield rifled home on the rebound to put Gers well on the way to three points in the 52nd minute, while substitute Kyle Lafferty scored on the counter with a quarter of an hour remaining.
Blair Alston tucked home a late penalty after being tripped by Connor Goldson, but it was scant consolation on a painful day for Saints, who remain in eighth place.
Their misery was compounded when Daniel Candeias struck in the 79th minute, taking his time to finish off after being teed up by Arfield.
