Ronny Deila refused to blame the officials for Celtic's defeat to Dundee United, but told his sloppy players its time to sharpen up. Jackie McNamara's side halted the Hoops' run of eight successive league wins as they moved to within four points of the Scottish Premiership leaders with a 2-1 win. Stefan Scepovic had a goal wrongly chalked off for offside late on as United held on for their first victory over the Glasgow giants since May 2012. Celtic manager Ronny Deila (right) watches on during his side's 2-1 loss to Dundee United at Tannadice Park Deila refused to point the finger at referee Steven McLean or his assistants, but the Norwegian did reveal his anger at the way his team allowed Nadir Ciftci and Stuart Armstrong space to put the home side in front.
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Dundee United halted Celtic's run of eight successive league wins
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Jackie McNamara's side have moved within four points of Celtic
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Ronny Deila's team still lead the Scottish Premiership
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Nadir Ciftci and Stuart Armstrong scored for Dundee
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Leigh Griffiths fired in a late consolation for Celtic
Stuart Armstrong (second left) celebrates after he doubles @placeholder's advantage in the 65th minute