Jan Vennegoor of Hesselink kept Celtic's Clydesdale Bank Premier League title hopes alive with a last-gasp winner against leaders Rangers in an explosive Old Firm derby.
Shunsuke Nakamura's magnificent opener in the first half was cancelled out by substitute Nacho Novo shortly after the break, before Carlos Cuellar saw red for handball on the line with 20 minutes to go.
Scott McDonald failed to net from the penalty but an injury-time winner from Vennegoor of Hesselink could prove to be one of Celtic's most important goals of the season.
The Hoops now trail Rangers by a single point, although the Ibrox club have two games in hand as they chase their first title in three years.
Home boss Gordon Strachan named an unchanged side following the morale-boosting 4-1 win over Motherwell at the weekend, while Walter Smith made wholesale changes to the side who disposed of Partick Thistle to book a place in the Scottish Cup semi-finals.
Kevin Thomson - who grabbed the only goal in last month's Old Firm clash at Ibrox - missed out through suspension, with Steven Smith, Chris Burke, Novo, Kris Boyd and Steven Naismith also dropping out of the starting XI.
In came skipper Barry Ferguson, Steven Davis, Lee McCulloch, Sasa Papac, Kirk Broadfoot and Jean-Claude Darcheville.
The tone was set in the opening minute when Barry Robson clattered into Christian Dailly with elbows showing and the Rangers man's furious response to the clumsy challenge earned both players a lecture from referee Kenny Clark.
Celtic then passed up a great opportunity to open the scoring when Nakamura sent Jan Vennegoor of Hesselink through on goal with only Rangers goalkeeper Allan McGregor to beat.
But the striker's first touch was poor and McGregor raced off his line to block before Papac hooked to safety.
There was concern for Rangers when McCulloch required treatment following a lunging tackle from Paul Hartley, which earned the Celtic midfielder a booking, but McCulloch was soon back involved in the action.
Celtic were threatening again when Robson swung a corner into the packed goalmouth and Gary Caldwell saw his downward header cleared away by Steven Whittaker.
But the home side's hard work paid off when they opened the scoring in the 20th minute.
McGregor headed into this game with a record-breaking four consecutive clean-sheets against Celtic but was powerless to prevent this stunning effort from leaving the net from bulging.
Nakamura collected a Caldwell ball 30 yards out and took a touch before rifling an unstoppable swerving shot just inside McGregor's right-hand post.
Broadfoot was next into the referee's book 10 minutes later for a foul on Aiden McGeady.
Celtic were clearly boosted by the goal and could have snatched another when Scott McDonald surged down the right flank and had a go from a tight angle, but his shot was batted away by McGregor at the near post.
Darcheville was Rangers' biggest threat in the first half and tried to restore parity before half-time, but he blasted well over the crossbar from the edge of the box, before another effort was deflected narrowly wide of the upright.
Both sides took advantage of the interval to make changes in personnel, Celtic swapping Lee Naylor for Mark Wilson and Rangers throwing Novo into the action in place of Broadfoot.
Novo was on the park for just six minutes when he was the victim of a cynical challenge from Vennegoor of Hesselink, which earned the Dutchman a yellow card.
But, more importantly for Rangers, the tiny striker recovered to haul Rangers back into the game after 55 minutes.
Wilson made a clearance before going to ground but no foul was forthcoming and he was still flat out on the pitch when the ball broke to Whittaker.
He slipped a great pass through to Novo and the Spaniard bulleted past the outstretched hands of Boruc into the back of the net.
The equaliser sparked wild scenes in the Rangers dug-out, with the unstripped Naismith booked for running onto the pitch to celebrate.
Rangers were dealt a blow when Cuellar was sent off with 20 minutes remaining for using his hand to deflect a netbound Nakamura shot onto the crossbar and referee Clark immediately pointed to the penalty spot.
McGregor appeared to be in come discomfort with an ankle injury but was again the hero for Rangers when he blocked McDonald's spot-kick at his left-hand post, with the Australian denied a great opportunity to claim his first Old Firm derby goal.
The goalkeeper then received treatment for several minutes in his goalmouth and there was further controversy when the Rangers doctor appeared to be hit with a missile from the crowd, before McGregor eventually hobbled off to be replaced by Neil Alexander.
Cuellar's red card almost looked set to be a price worth paying as the game entered injury-time, with the scores still level.
A draw would have almost been as valuable as a win for Rangers.
But Alexander had to pick the ball out of the back of his net deep into injury-time when McDonald nodded into the path of Vennegoor of Hesselink who sent a header over the line from a few yards.
The final whistle sparked scenes of chaos with players from both sides battling on the pitch, as Celtic fans celebrated their late, late win.
