Dundee United ended Celtic's eight-game winning run in the Scottish Premiership with a 2-1 victory at Tannadice on Sunday.
The result moves Jackie McNamara's men into second place, above Aberdeen on goal difference, and cuts the gap on the leaders to four points.
Nadir Ciftci gave United the lead after only five minutes and Stuart Armstrong doubled their advantage midway through the second half.
Stefan Scepovic had an effort disallowed before fellow substitute Leigh Griffiths pulled one back for Celtic with three minutes left.
Griffiths was denied by the post in stoppage time as Dundee United made it seven wins out of nine in the Premiership at Tannadice this season.