Hibernian consigned Celtic to a third Scottish Premiership defeat of the season and prevented the champions returning to the top of the table.
Vykintas Slivka struck after 46 seconds and Florian Kamberi finished a superb second-half counter attack with an emphatic finish.
Substitute Lewis Morgan fired narrowly wide in Celtic’s best chance.
And they could finish the weekend in third if Rangers beat Hamilton later.
Brendan Rodgers’ team will, however, still have a game in hand over the Ibrox side.
Hibs, meanwhile, will prepare for the second of their three home matches this week against Rangers on Wednesday.
Celtic caught cold by Hibs’ quick thinking
Hibs’ intent was clear from kick-off as Emerson Hyndman and Oli Shaw moved the ball left to right for Slivka, who cut inside Jozo Simunovic to sweep a shot beyond Craig Gordon.
Slivka took a sore one after being on the end of a late lunge by Scott Brown, who was booked, and the midfielder did not reappear for the second half.
But his replacement Sean Mackie played a major role in the hosts’ second as Neil Lennon’s side broke from a Celtic corner and Mackie’s diagonal ball was collected by Kamberi and lashed past Gordon.
It could have been worse for Celtic, with Stevie Mallan’s first-half free-kick and dipping long-range drive in the second period beaten away by Gordon.
Celtic looked to James Forrest for inspiration and he twice had dangerous balls cut out with Odsonne Edouard waiting to convert a tap-in, and the winger also drew a save from Ofir Marciano.
Edouard was booked for simulation after going down in the wake of Steven Whittaker’s challenge right on the edge of the box, though replays suggested there may have been some contact.
Morgan, Jonny Hayes and Mikey Johnston were sent on to give the visitors more impetus and Morgan was inches away from halving the deficit after inventive play by Johnston.
‘Lennon gets answer he was looking’ – analysis
BBC Scotland’s Brian McLauchlin at Easter Road
Hibernian boss Neil Lennon said pre-match he would know within the opening five minutes what the attitude and application of his players was going to be against champions Celtic.
Well he only had to wait 46 seconds when they gave the manager the answer he was looking for.
In recent weeks the management team at Easter Road have been extremely critical of their players but on this performance they should receive nothing but praise.
The centre-back pairing of Efe Ambrose and 19-year-old Ryan Porteous was solid. Stevie Mallan and Emerson Hyndman never gave the Celtic midfield a sniff and Oli Shaw was tireless in his work-rate alongside Flo Kamberi, who put in his finest performance of the campaign.
Celtic boss Brendan Rodgers was without four key players and changed formation with Kristoffer Ajer slotting into a back three but they should still have enough in their locker to test a Hibernian side who have struggled in recent weeks.
With key games to come before the break including a visit to Ibrox, Rodgers will be keen to have the likes of Ryan Christie and Kieran Tierney back sooner rather than later and the Celtic fans will be looking for the squad to be freshened up in the January transfer window with strikers a priority.