It took Neil Lennon's men until the 64th minute to open the scoring in a 2-0 victory over Hearts, with Kris Commons slotting home for his ninth league goal of the season.
James Forrest added a second in stoppage time to extend the Glaswegians' lead to 10 points at the summit, while Hearts will have been glad to escape the 7-0 drubbing they suffered against the same opponents in the Scottish Cup earlier in December.
Celtic's title hopes were boosted by Inverness' failure to beat Aberdeen in a true game of two halves that ended 4-3 in favour of Derek McInnes' men.
The visitors raced into a 4-0 half-time lead at Caledonian Stadium thanks to two goals from Barry Robson - one from the penalty spot - and further strikes from Peter Pawlett and Niall McGinn.
However, John Hughes' side roared back after the break, reducing their deficit to one courtesy of a Billy McKay brace and a stoppage-time header from Graeme Shinnie.
Inverness were unable to complete a stunning comeback as they fell to their first defeat under Hughes and a first league reverse since October 20.
The result sees Inverness slip to fourth with Aberdeen climbing into third based on goals scored, and Dundee United occupying second on goal difference after a 1-0 win over Ross County.
Gary Mackay-Steven netted the only goal as United recorded a fifth successive victory.
Elsewhere, Kilmarnock recorded a 2-1 victory over Partick Thistle, who have now gone six matches without a win, while Motherwell picked up back-to-back victories for the first time since September, beating St Mirren 3-0 to put themselves firmly in the mix in the chase for a European berth.
Meanwhile, Hibernian extended their winless run to eight in a goalless draw with St Johnstone.
