Celtic's push for a second successive Bank of Scotland Premier League title suffered another setback at Tannadice after a stunning late equaliser from Dundee United gave the home side a 1-1 draw.
Dubliner Jon Daly crashed the ball home from the edge of the Celtic penalty area in injury time for his first goal since arriving from Hartlepool in January.
United by that stage had been reduced to 10 men, with Barry Robson sent off, but the point was well earned.
Celtic took the lead when Shunsuke Nakamura curled in a magnificent free-kick just after the interval.
And when Robson was dismissed in the 89th minute for head-butting Lee Naylor off the ball the home side's hopes looked forlorn.
But Daly scored two minutes into injury time with a terrific half-volley, as Celtic's disappointing recent form - which saw them lose to Rangers and Falkirk in their previous two games - continued.
The home side suffered a blow ahead of the game as Keith Watson, who was named in their starting line-up, sustained a knee injury while warming up and Stuart Duff had to be hastily ushered into the team.
That did not stop United settling into the match quicker than Celtic though, as the visitors were uncharacteristically wasteful in possession during the early stages.
In a good spell for the home side, Mark Kerr flashed a drive just past Artur Boruc's left-hand post, before Celtic eventually threatened when Gary Caldwell - appearing for the first time since suffering a knee injury in November - headed wide from Nakamura's corner.
Celtic's playmaker then almost created a goal with a tantalising cross, which was flicked away by David McCracken as Jan Vennegoor of Hesselink lurked menacingly.
Just as Celtic were starting to exert more influence on proceedings though, Robson tested Boruc with a free-kick which was well saved, before the Polish keeper carelessly spilled another drive from Robson, although there were no United players on hand to take advantage of the mistake.
Boruc continued this erratic form in the 31st minute, as he lost the flight of a Steven Robb cross in the air and was thoroughly relieved to see the ball smack against the face of his crossbar.
But Celtic responded well from that let-off and went on to create their best opening of the first half two minutes later.
Neil Lennon was the architect in sliding a smart pass into the path of Craig Beattie, only for the striker to take an abysmal first touch and a brave diving intervention from Derek Stillie thwarted the danger.
In an effort to make up for his poor control, Beattie went in with his studs showing while challenging the United goalkeeper and was promptly booked for the foul.
Stillie then had to parry a searing drive from Aiden McGeady, while at the other end of the park, Collin Samuel was unfortunate to pull his right-footed shot just wide.
However, for all their positive efforts during the opening period, United fell behind three minutes after the restart to a stunning Nakamura set-piece.
McCracken fouled Vennegoor of Hesselink 25 yards from goal and Nakamura curled a sumptuous shot over the United wall and past a stranded Stillie.
The home side took some time to find their feet following the concession of that goal, but 10 minutes later, Robson flashed a snap shot wide, before the United captain hit the side netting with a free-kick that failed to emulate Nakamura's earlier effort.
Celtic finally fashioned another good opening with 17 minutes remaining, when a neat passing exchange from Vennegoor of Hesselink and McGeady allowed the Dutchman to shoot wide, before Robson was dismissed for clashing with Naylor.
However, despite going a man down, the home side refused to accept defeat and when Duff's long ball found Daly, the United striker chested the ball down and launched a brilliant shot past Boruc to secure an unlikely share of the spoils.
