A trademark free-kick from Shunsuke Nakamura in the dying minutes gave Celtic a hard-earned victory over St Mirren at Love Street.
The Buddies could have twice taken the lead through David Van Zanten and Billy Mehmet, forcing two fine saves from Celtic keeper Artur Boruc.
Scott McDonald could have opened the scoring for Celtic after 30 minutes, but his glancing header went wide.
The win extended Celtic's lead over third-placed Motherwell to 14 points.
Celtic piled on some early pressure, with Georgios Samaras giving the Saints defence some food for thought in the opening minutes of the match.
Nerves soon settled and St Mirren's Will Haining tried his luck with a 30-yard drive that went wide of Boruc's goal on five minutes.
Barry Robson's free-kick on the edge of the penalty area near the 15-minute mark looked promising, but failed to make it past the St Mirren defence.
Aiden McGeady broke free on the right in the 21st minute and headed for goal, but his shot drifted across the face of goal.
With 30 minutes elapsed, McGeady fired in a low cross from the left, but Australian striker McDonald's header went wide.
As half-time approached, Celtic's early composure gave way to slack passing and poor possession, while St Mirren looked confident in midfield, despite few chances of their own up front.
In the 37th minute, Craig Dargo sprinted down the right and sent in a cross in to Van Zanten in the penalty area, but Boruc pulled off a superb save to maintain the deadlock and the teams headed in for the break.
Following the restart, Celtic looked more determined and restored some of their early pressure, but St Mirren remained tenacious and well organised.
Samaras sprinted across the face of the St Mirren penalty area in the 55th minute, but his final ball went wide.
St Mirren continued to frustrate their visitors, and Mehmet forced another fine save from Boruc with an hour played when he struck from the heart of Celtic's penalty area and the Polish keeper deflected the powerful shot.
McDonald latched on to a neat McGeady cross in the 75th minute, but once again his header drifted wide.
606: DEBATE
With 10 minutes remaining, Lee Naylor fired in a volleyed shot from distance, but the ball sailed wide of the mark.
Celtic's Chris Killen could have nicked a goal in the final five minutes when he headed in a long ball, but his mistimed effort was badly off target.
The deadlock was finally broken in the last two minutes when Nakamura appeared to be felled by Gary Mason outside the St Mirren penalty area and lined up a 25-yard free-kick.
The Japanese international found the bottom right-hand corner of Howard's net to salvage a win for Celtic.
St Mirren: Howard, van Zanten, Haining, Potter, Maxwell, Murray, Dorman, Mason (Corcoran 90), Barron, Mehmet, Dargo (Kean 80). Subs Not Used: Mathers, Hamilton, Miranda, McCay, McGinn.
Booked: Barron, Murray.
Celtic: Boruc, Hinkel, Caldwell, McManus (O'Dea 53), Naylor, Robson (Nakamura 64), Scott Brown, Donati, McGeady, Samaras (Killen 77), McDonald. Subs Not Used: Mark Brown, Hartley, Sno, Hutchinson.
Booked: McGeady, Donati.
Goals: Nakamura 87.
Att: 7,213
Ref: E Smith
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