Match ends, Dundee United 2, Celtic 1.
Dundee United 2-1 Celtic
- United win to go second in Premiership
- Ciftci and Armstrong score goals for hosts
- Griffiths nets for Celtic
- Leaders' third league defeat of campaign
Dundee United beat Celtic to go second in the Premiership and move to within four points of the league leaders.
Nadir Ciftci held off the challenge of Efe Ambrose to fire United into an early lead.
Celtic hit the frame of the goal twice before Stuart Armstrong got the hosts' second by nodding in Ciftci's cross.
Leigh Griffiths finished well to reduce the visitors' deficit and came very close to an equaliser when his low strike came back off the post.
Jackie McNamara's side went ahead of Aberdeen on goal difference, while Ronny Deila's team, who had won their previous eight league games, suffered their first top-flight defeat since early October and their third overall this season.
Ciftci had an eventful opening to the match, getting booked in the first minute for a clumsy tackle on Scott Brown before finding the net.
Armstrong's deflected pass evaded Ambrose and Ciftci's close control and strength allowed him to brush off the Nigerian defender's attempt at a recovery and lift the ball past goalkeeper Craig Gordon.
Celtic's response was to stretch United on the flanks and both James Forrest and Stefan Johansen troubled the home defence without achieving a telling delivery.
However, Johansen was in on goal after playing a one-two with John Guidetti and goalkeeper Radoslaw Cierzniak was quick off his line to make the block.
United remained dangerous in attack, though, and Conor Townsend drew a save from Gordon after venturing forward from left-back.
Guidetti went down in the box after being closed down by Sean Dillon - prompting loud shouts for a penalty from the travelling fans - but referee Steven McLean said Dillon's challenge was a legitimate shoulder charge.
United's resistance was further tested when Cierzniak's attempted clearance from a Johansen corner ricocheted on to the crossbar off Nir Bitton's head and Virgil van Dijk's rebound header was cleared off the line by Jaroslaw Fojut.
Ambrose continued to struggle with the threat of Ciftci in the second half and conceded possession too easily on one occasion, leading to the striker testing Gordon with a low shot.
Dillon almost scored an own goal when his header from Anthony Stokes's cross looped up and bounced off the right-hand post, Forrest unable to convert the rebound.
Stokes then headed off target moments before he and Guidetti were replaced by Kris Commons and Stefan Scepovic.
However, it was United's attackers who made the most impact in the wake of the double change with Ciftci's perseverance again proving crucial.
This time, the Turkish forward held off Emilio Izaguirre on the right and dinked the ball to the back post for the unmarked Armstrong to head off Gordon and into the net.
Scepovic thought he had reduced Celtic's deficit when he finished crisply from Izaguirre's chested pass, but the offside flag cut short the substitute's celebrations. However, television replays showed the Serbian had been onside.
Izaguirre cleared Chris Erskine's header off the line moments later and the end-to-end nature of the contest continued when Bitton's replacement, Griffiths, ran on to Commons' pass and placed the ball firmly past Cierzniak for Celtic's goal.
The visitors hit the woodwork for a third time when Griffiths' effort from around 20 yards struck Cierzniak's left-hand post in stoppage time.
- 7CiftciBooked at 1minsSubstituted forDowat 82'minutes
- 5van Dijk
- 6BittonSubstituted forGriffithsat 78'minutesBooked at 80mins
- 9GuidettiSubstituted forScepovicat 60'minutes
- 10StokesSubstituted forCommonsat 60'minutes
- Steven McLean
- Shots on Target
Second Half ends, Dundee United 2, Celtic 1.
Corner, Dundee United. Conceded by Emilio Izaguirre.
Blair Spittal (Dundee United) wins a free kick in the defensive half.
Foul by Stefan Johansen (Celtic).
Leigh Griffiths (Celtic) hits the right post with a left footed shot from outside the box.
Attempt saved. James Forrest (Celtic) right footed shot from the left side of the box is saved in the centre of the goal.
Foul by Ryan Dow (Dundee United).
Emilio Izaguirre (Celtic) wins a free kick on the right wing.
Goal! Dundee United 2, Celtic 1. Leigh Griffiths (Celtic) left footed shot from the centre of the box to the centre of the goal. Assisted by Kris Commons.
Calum Butcher (Dundee United) wins a free kick in the attacking half.
Foul by Scott Brown (Celtic).
Attempt missed. Virgil van Dijk (Celtic) header from the centre of the box is close, but misses to the right following a set piece situation.
Foul by Jaroslaw Fojut (Dundee United).
Leigh Griffiths (Celtic) wins a free kick in the defensive half.
Attempt blocked. Chris Erskine (Dundee United) right footed shot from the centre of the box is blocked.
Corner, Dundee United. Conceded by Stefan Johansen.
Substitution, Dundee United. Ryan Dow replaces Nadir Ciftci.
Leigh Griffiths (Celtic) is shown the yellow card.
Nadir Ciftci (Dundee United) wins a free kick in the defensive half.