Aberdeen dramatically cut Celtic's lead at the top of the Ladbrokes Premiership to three points with a 2-1 win over the Hoops, piling further pressure on Parkhead boss Ronny Deila.
Hopes of a domestic treble for the Glasgow club had ended with a League Cup semi-final defeat to Ross County at Hampden Park on Sunday but there was to be no redemption for the Norwegian in the league.
The visitors had looked in control of the match until the 31st minute when Dons wide-man Jonny Hayes, playing with a bandage on his hand after being bitten by a dog, scored with a thunderous drive from 25 yards before debutant Simon Church added a second before the break.
Aberdeen came out after the break fired up with confidence and could have added to their lead as the Hoops struggled unsuccessfully to get back in the game, with Leigh Griffiths' injury-time strike a mere consolation.
While Wales international Church, who joined on loan from MK Dons, was given his debut, Hoops skipper Scott Brown made his first start for more than two months after a substitute appearance against County.
New Danish defender Erik Sviatchenko, who also came off the bench at Hampden, was handed his first start.
Defender Efe Ambrose, sent off against the Staggies, dropped to the bench along with transfer deadline day signing Colin Kazim-Richards.
The early stages were understandably frantic but Celtic appeared to have it all in hand.
Celtic midfielder Nir Bitton's 35-yard free-kick required Dons goalkeeper Scott Brown to save at the second time of asking in the fifth minute with his Hoops' namesake blasting over his bar with a long-range effort 10 minutes later.
However, just over the half-hour mark the complexion changed when Hayes took possession of a loose ball contested by Adam Rooney and Bitton and hammered a drive high past the flailing Celtic keeper Craig Gordon at his near post.
The Parkhead men were stunned but fought back immediately and Brown parried another effort from Bitton to safety.
However, the Red Army were joyous again in the 38th minute when a Hayes corner was flicked on by midfielder Kenny McLean, with Church getting the final touch to the ball before it went in.
The first-half ended with Gordon saving a 25-yard thunderbolt from McLean and the Hoops in some disarray.
Kazim-Richards replaced Stuart Armstrong for the start of the second half to partner Griffiths in an unusual 4-4-2 formation which left them vulnerable at the back.
Aberdeen drove forward with confidence and Church dragged a shot wide from six yards after a goalmouth melee.
As play stretched and tension mounted, Griffiths headed a Brown cross past the post just before the hour mark before Niall McGinn drew a save from Gordon with an audacious long-range drive and Rooney headed just wide from the resultant corner.
Kazim-Richards was booked by referee Steven McLean for tangling with Dons defender Ash Taylor before Brown was yellow-carded for a foul on McGinn as tempers frayed.
Celtic huffed and puffed around the Aberdeen box and survived a stonewall penalty claim in their own when Rooney was fouled by Sviatchenko.
Griffiths pulled a goal back in the third minute of added time time but it proved academic, as the home side's Premiership aspirations hopes were handed a massive boost