GLASGOW, Scotland (AFP) — Kilmarnock ended a 57-year wait for a win at Celtic Park as goals in either half condemned the Scottish Premier League leaders to a 2-0 defeat.
Celtic, who suffered an agonising last-gasp defeat to Barcelona in midweek, showed all the signs of suffering from a European hangover as they made a sluggish start.
Joe Ledley somehow missed from close range for Celtic before Cillian Sheridan seized on some slack defending to race in on goal and calmly round Fraser Forster to net against his old club in the 43rd minute.
Forster kept the Hoops in the match with a superb stop from James Dayton but could do nothing to stop Liam Kelly's fiercely driven 62nd minute penalty after Emilio Izaguirre had clipped Rory McKeown in the box.
Izaguirre had a strike ruled out for offside and substitute Tony Watt fired over from six yards as Killie held on for their first win at Celtic Park since December 1955.
Celtic remain top by two points over Hibernian with a game in hand.
Celtic manager Neil Lennon said he was confused by his side's performance.
Elsewhere, Aberdeen moved up to third with a 2-0 win over Dundee, Dundee United won 1-0 away to St Mirren, Hearts drew 2-2 with Ross County and St Johnstone scored a last minute equaliser to claim a 1-1 draw with Inverness Caledonian Thistle.