Rangers 0 Celtic 2: Georgios Samaras scored twice as Celtic blew the title race wide open by claiming victory in the Old Firm derby at Ibrox.
The Hoops headed into the New Year showdown with a single point advantage at the top of the Clydesdale Bank Premier League, but aware of Rangers' two games in hand.
However, two second-half goals from Samaras - the second from the penalty spot - allowed Celtic to extend that lead to four points.
Youngster Jamie Ness was handed a memorable first start for Rangers after Steven Naismith failed to recover from a hamstring injury in time.
Celtic's new signing Freddie Ljungberg failed to even make the squad after picking up a virus, while captain Scott Brown was suspended. Beram Kayal, Charlie Mulgrew and Samaras were all drafted into the Hoops side.
Former captains John Greig and Billy McNeill led out the teams as both sets of fans perfectly observed a minute's silence ahead of kick-off to commemorate the 40th anniversary of the Ibrox Disaster, when 66 Rangers fans lost their lives. Rangers were also showing their respects to former player Avi Cohen, who died recently.
Celtic survived a scare when Lee McCulloch connected well with a Vladimir Weiss corner and Emilio Izaguirre was forced into a headed clearance via the crossbar as Rangers applied pressure early on.
Clear-cut chances were few and far between in a scrappy opening spell, but Celtic threatened when Paddy McCourt slipped a lovely pass to James Forrest in front of goal only for McCulloch to make a timely intervention before he could unleash a shot.
The first bookings of the game came after 27 minutes when referee Craig Thomson brandished a yellow card to Madjid Bougherra for a challenge on Mulgrew and the Celtic player was also cautioned for retaliating.
Steven Whittaker had the chance to snatch the opener at the end of a disappointing first half when he collected a flighted cross from Weiss, but he miskicked under pressure from Mark Wilson and the opportunity was lost.
Walter Smith and Neil Lennon no doubt both demanded better from their players during their half-time team talks and it was Celtic who could have grabbed the advantage shortly after the restart when McCourt pounced on a Samaras flick-on only to rifle across the face of goal.
The game was badly in need of a goal and Steven Davis lofted over several Celtic players into the path of Kenny Miller but goalkeeper Fraser Forster raced off his line to clear.
The match eventually sparked into life after 62 minutes when Samaras opened the scoring for Celtic.
Richard Foster lost possession to Joe Ledley, who punted the ball forward for Samaras to race past Allan McGregor, who had charged yards outside his box, before coolly slotting home.
Celtic doubled their lead seven minutes later when the referee pointed to the penalty spot after Bougherra clipped Samaras in the box. The Greece international dusted himself down before sending a firm, low shot past McGregor.
Rangers faced the daunting task of hauling themselves back into the game but could have given themselves a lifeline had Bougherra's volley in front of goal been on target following good work from Sasa Papac.
With time fast running out for the Scottish champions, substitute Kyle Lafferty could have netted from a free-kick just outside the box but his effort failed to make it past the Celtic wall.
Samaras was then denied his hat-trick by a fingertip save from McGregor as Lennon's men returned to Parkhead with the points.