Match ends, Aberdeen 2, Celtic 1.
Aberdeen inflicted a first league defeat of the season on Celtic with their second victory over the champions in a matter of weeks.
Celtic had Virgil van Dijk sent off for a last-man challenge on Peter Pawlett after just 12 minutes.
Jonathan Hayes's shot flew into the top corner to give Aberdeen the lead, before Adam Rooney headed in a second.
Substitute James Forrest gave Celtic a lifeline to make it a nervy second half, but the Dons held on.
With Celtic's 26-game unbeaten run went Fraser Forster's clean sheet record, and the last five goals the English goalkeeper has now conceded domestically have been to Derek McInnes's men.
The Dons' victory follows their win in Glasgow when they knocked holders Celtic out of the Scottish Cup.
With Motherwell losing to St Johnstone, the Dons now move four points clear in second spot in the Scottish Premiership as they close in on Europa League qualification.
Celtic started the game on the front foot and twice had Aberdeen living dangerously inside the opening minutes.
Ex-Don Charlie Mulgrew slipped inside his marker and drilled a low ball at Jamie Langfield, before Anthony Stokes almost scrambled Scott Brown's low cross over the line, only for Mark Reynolds to make a timely intervention.
It was a good start from the visitors, but manager Neil Lennon's game plan was turned on its head inside the first quarter of an hour.
Mulgrew gifted away possession, leaving Van Dijk the last man against two red shirts. The big Dutchman mistimed his challenge and sent Pawlett sprawling on the edge of the box, and referee Craig Thomson reached straight for the red card.
Rooney was inches away from connecting with Hayes's cross but, that chance apart, it seemed Aberdeen did not quite know what to do with their one-man advantage and Celtic still looked the more comfortable of the two sides.
Nir Biton forced a great one-handed save from Langfield, with the rebound narrowly evading Leigh Griffiths.
However just as Forster looked set to extend his clean sheet record into half-time, it was blown apart by two quick-fire Aberdeen goals.
First Niall McGinn found Hayes in space, and the Irishman cracked a stunning 30-yard effort into the top corner that the Celtic shot-stopper could not get anywhere near, the first league goal he had conceded in 1,256 minutes.
That lifted Pittodrie, and soon the lead was doubled when Rooney's diving header directed McGinn's cross into the corner of the net to give the hosts a commanding half-time lead.
Celtic still had an unbeaten league run to preserve, and a dominant 15-minute spell of pressure finally brought its reward when Tate's clearance was unconvincing, and Forrest was given space to fire Brown's lay-off into the roof of the net.
Aberdeen had been happy to sit back and let Celtic have possession, but now they needed a response.
Hayes and Barry Robson tested Forster from distance, but the nerves were evident amongst the home side as Lennon's men continued to have the initiative.
Stokes and Samaras both tried their luck from distance, but Celtic could not get in behind the Dons defence.
McInnes threw on Russell Anderson and Joe Shaughnessy with Aberdeen rooted in their own half.
The Dons could have settled nerves when McGinn was sent clear on the right late on.
He had space for the shot but instead tried to find Pawlett in the middle, and his ball across goal was poor.
- 29LoganSubstituted forAndersonat 83'minutes
- 5ConsidineBooked at 9mins
- 28TateSubstituted forShaughnessyat 83'minutes
- 8FloodBooked at 82mins
- 16PawlettSubstituted forVernonat 90+2'minutes
- 3IzaguirreSubstituted forBaldeat 89'minutes
- 4AmbroseBooked at 22mins
- 5van DijkBooked at 13mins
- 15CommonsSubstituted forForrestat 45'minutes
- 28GriffithsBooked at 18minsSubstituted forSamarasat 77'minutes
- Craig Thomson
- Shots on Target
Second Half ends, Aberdeen 2, Celtic 1.
Jonathan Hayes (Aberdeen) wins a free kick in the defensive half.
Foul by Amido Baldé (Celtic).
Substitution, Aberdeen. Scott Vernon replaces Peter Pawlett.
Substitution, Celtic. Amido Baldé replaces Emilio Izaguirre.
Joe Shaughnessy (Aberdeen) wins a free kick on the left wing.
Foul by Georgios Samaras (Celtic).
Corner, Celtic. Conceded by Willo Flood.
Substitution, Aberdeen. Russell Anderson replaces Shaleum Logan.
Substitution, Aberdeen. Joe Shaughnessy replaces Alan Tate.
Willo Flood (Aberdeen) is shown the yellow card.
Foul by Willo Flood (Aberdeen).
Emilio Izaguirre (Celtic) wins a free kick in the defensive half.
Foul by Willo Flood (Aberdeen).
Nir Biton (Celtic) wins a free kick in the attacking half.
Attempt blocked. Georgios Samaras (Celtic) right footed shot from outside the box is blocked.
Attempt saved. Anthony Stokes (Celtic) right footed shot from outside the box is saved in the bottom right corner.
Foul by Barry Robson (Aberdeen).
Anthony Stokes (Celtic) wins a free kick in the defensive half.