The bid for automatic European qualification via third spot is now out of Aberdeen’s own control and they only have themselves to blame.
Defeat to Celtic had further repercussions beyond the Parkhead club securing an eighth straight league and edging closer to an historic treble Treble.
It allowed Kilmarnock to leap-frog the Dons into third position with just two games remaining.
If Aberdeen win their remaining games against Hearts and Hibs it still may not be enough if Killie, who hold a six goal advantage, also take maximum points.
Ultimately, Aberdeen’s lack of decisiveness both in their own box and Celtic’s was their downfall.
Two glorious chances were spurned by on-loan striker James Wilson in the first half.
Slack defending from the Reds in their own box then gifted Celtic their first two goals. The defending champions only needed a point to win the title.
Aberdeen boss Derek McInnes watched from the stands having been hit with a one-game ban by the SFA for reacting to sectarian abuse from Celtic fans during the 3-0 Scottish Cup defeat.
It was a ridiculous call from the SFA who have set a dangerous precedent by punishing a manager for reacting to abuse.
How depressingly predictable that McInnes was again the target of those sectarian chants from Celtic supporters at Pittodrie.
For too long these vile songs have been heard at Scottish games. Now is the time to take a zero tolerance stance on the culprits to wipe it out.
Back to the football, which is what we should be concentrating on in the aftermath of a game between two of the country’s top sides, at which a title was won.
Aberdeen were ravaged by injury, particularly in the wide creative areas, but there was still enough quality in the starting 11 to be competitive and get a result.
Celtic dominated the first 10 minutes, when keeper Joe Lewis had to save sharply from Tom Rogic, but then the Dons found their rhythm and confidence.
Aberdeen should have netted in the 17th minute when Stevie May clipped a cross to James Wilson 12 yards out.
Wilson drilled a half volley into the ground that bounced over beaten keeper Scott Bain and clipped the bar.
Then Odsonne Edouard broke clean in on goal when chasing a 40-yard ball, but Lewis raced off his line to superbly save.
Next, Scott McKenna embarked on a rampaging run down the left flank before unleashing a glorious weighted cross behind the defence to pick out Cosgrove.
The striker’s first time shot from 12 yards was blocked by Bain, but the ball fell to Wilson who, with the keeper stranded, clipped the outside of the post from 12 yards out.
Aberdeen had only kept three clean sheets in their last 73 meetings with Celtic. Failure to take chances has a tendency to come back to haunt you against them.
So it proved in the 39th minute when Callum McGregor was allowed far too much time to flight in a cross from the left.
Mikael LUSTIG evaded marker Stevie May who had switched off and met the ball with a diving header which flew past Lewis.
It was 2-0 in the 52nd minute when a corner from McGregor found Jozo SIMUNOVIC who rose above Scott McKenna to power home a header.
In the 88th minute, Odsonne EDOUARD cut inside at the edge of the penalty area and drilled a low shot beyond Lewis.
It sparked a mass exodus of Aberdeen supporters.
Is there a more hollow, depressing feeling in football than trudging out of your own ground after a defeat that handed your rivals the league title crown?
Walking down Pittodrie Street as you hear the party going on inside your own stadium?