Aberdeen brought Celtic's run of 17 successive league wins to an end with a spirited draw at Pittodrie.
Running on to a Kris Commons pass, Anthony Stokes rounded Dons keeper Jason Brown to squeeze home a shot in the 28th minute.
But Andre Blackman diverted Gavin Rae's shot into his own net just before the half-time interval.
In a match of few chances, Aberdeen striker Scott Vernon came closest in the second half, heading narrowly wide.
Aberdeen and Celtic are now the only clubs in the Scottish Premier League unbeaten in 2012, with the Dons remaining in seventh place on 33 points, while Celtic have a 21-point advantage over Rangers at the top.
The versatile Charlie Mulgrew was given a central midfield role and went close to opening the scoring with a fabulous curling free-kick that cannoned off the upright, with Brown flapping at thin air.
The visitors were claiming a penalty when Rae appeared to handle but referee Craig Thomson allowed play to continue.
The deadlock was broken when Commons slipped a great pass through to Stokes inside the Dons penalty area and the Irishman skipped past Brown to strike a low shot that evaded Andrew Considine on the line.
Shortly after the half-hour, Rory McArdle brought Blackman down on the edge of the Aberdeen box but Brown got down smartly to beat away a low curler from Stokes.
Moments later, Fraser Fyvie's shot from 12 yards was deflected over the bar for a corner as the Dons desperately tried to find a leveller before the interval.
And that goal duly arrived when Blackman turned the ball into his own net after Rae aimed a shot towards the Celtic goal from Vernon's threaded pass.
Shortly after the restart, Dons striker Rory Fallon missed a chance to give his side the lead after Ryan Jack crossed from the right, then Stokes was lucky to avoid punishment for angrily clattering into Jack.
A long-range effort by Kari Arnason sailed over the visitors' bar as Celtic struggled to find any passing fluency.
With an hour played, Mitch Megginson blundered a chance to hand the Dons the lead when he broke free inside the Celtic penalty area and sent a shot wide of the mark.
Aberdeen continued to look dangerous when Vernon sent a header wide of the target from close range.
Stokes could have netted his second of the afternoon in the 77th minute, but his half-volley from a tight angle far on the right was smothered by Brown.
In a frantic final 10 minutes, Celtic found themselves under pressure - Peter Pawlett failing to connect with a pass inside the visitors' penalty area as Aberdeen sensed an opportunity to snatch a winner.
A Mulgrew cross from wide on the left failed to find a Celtic jersey in the Aberdeen penalty area as Considine made the clearance, then Victor Wanyama's shot was deflected from the edge of the area.
A flurry of Celtic corners failed to yield a winner in the four minutes of added time and Celtic's long winning run came to an end.