Sam Cosgrove became the first Don to score 20 goals before Christmas since Duncan Shearer in 1992 but it is doubtful he felt like celebrating the feat on Saturday.
His joy at scoring was tempered by a red card which looked harsh and with his departure went Aberdeen’s hopes of getting something from the game at Celtic Park.
The Dons competed gamely against the Hoops but Cosgrove was the only serious threat for Derek McInnes’s side and when the visitors’ late push for an equaliser came the absence of the talisman attacker was telling.
For Dons boss Derek McInnes, the loss of his striker was the decisive factor.
He said: “I spoke to the referee and he thinks when Sam led with his leg he caught the player but he hasn’t.
“I’ve watched it and Cosgrove wins the ball cleanly. If he hits the player at speed you can understand why he is sent off but he has won the ball cleanly.
“Big Ajer is lying on the ground winking and laughing at the boy.
“If Cosgrove hits Ajer going at that speed the boy is hurt.
“No way is it a red card. Neil Lennon thinks we have been harshly treated. Would it have changed the outcome?
“I don’t know. Celtic are a strong team going well but certainly the red card altered our approach.”
There was an early warning for the Dons as Hoops defender Christopher Jullien saw his header from Ryan Christie’s corner come back off the crossbar.
Unfortunately for the visitors, that warning was not heeded as the same two players combined at the next corner in the seventh minute to put the champions ahead.
It was Christie’s delivery which found Jullien in space in the box and his side-footed effort bounced up and past Dons captain Joe Lewis into the net.
For Celtic it was an early award for their pressure but for Aberdeen it was such a poor goal to concede.
The pattern was set from Julien’s opener with the home side piling on the pressure in pursuit of a second goal while Aberdeen’s aim was simply to stay in the game.
It was a difficult task with Odsonne Edouard in the mood for this one and it took a fine save from Lewis to deny the Hoops forward in the 20th minute.
It was near one-way traffic towards the home goal and Aberdeen’s best hope of a goal looked to be from set piece opportunities of their own.
The first, a free kick low to Scott McKenna, ended with the defender fluffing his lines and having a fresh air swipe at the ball, but the second produced an equaliser 10 minutes before the break.
James Wilson’s ball was not cleared by the home defence and the ball was worked out right to Niall McGinn and the Northern Ireland international’s delivery was inch-perfect as he found Sam Cosgrove and the striker beat Fraser Forster with a bullet header from six yards to make it 1-1.
Celtic were stunned and the disbelief among the home support soon turned to anger towards official Euan Anderson for his decision to book Christie for diving and then dismiss appeals for a penalty after Edouard went down under a challenge from Wilson.
The pattern of play continued after the break with the Hoops peppering Lewis’ goal with long-range efforts, all of which were comfortably dealt with by the Aberdeen captain, but the game swung in the home side’s favour following two key moments midway through the second half.
The first moment was Edouard’s goal in the 66th minute which came from a surging run from Kris Ajer followed by a pass to Edouard.
The striker played a quick one-two with Christie before running clear on goal and firing past Lewis.
The second, and arguably more damaging, was the straight red card which followed for Cosgrove three minutes later.
Substitute Jon Gallagher tested Ajer with a run down the right wing. The Hoops defender timed his challenge well to stop Gallagher but as he tried to clear the danger Cosgrove slid in with a powerful challenge of his own to put the ball out for a throw-in.
Referee Anderson thought otherwise and had no hesitation in brandishing the red card to Cosgrove, who was incredulous.
Home captain Scott Brown was quick to let the Dons striker know what he thought of the challenge and the skipper was pushed away by the departing forward as he made his way down the tunnel.
His side’s hopes of getting something from the game went with him.