GOALS by Scott McDonald and Georgios Samaras against Inverness at Parkhead kept the pressure on Clydesdale Bank Premier League leaders Rangers.
However, the home side were made to sweat a little in the closing stages of a game that they had under control for most of the 90 minutes.
Australian international McDonald's 25th goal of the season right on the interval gave the champions the lead and his Greek team-mate bulleted an Aiden McGeady cross past Michael Fraser on the hour mark.
But the final minutes were needlessly fraught for Celtic. Caley striker Marius Niculae took advantage of Scott Brown's misplaced pass to pull a goal back in the 70th minute but the home side survived an nervy end to the game and remain four points behind their Ibrox rivals at the top of the table.
Caley were the last side to beat Celtic in the league, inflicting a 3-2 defeat on the champions in December but there was little danger of a repeat on this occasion.
The swathes of empty seats inside Celtic Park at kick-off suggested that many stay-away fans anticipated a routine victory but the first half was something of a slog.
Celtic manager Gordon Strachan, serving the first of a two-match touchline ban, watched a tepid opening to the match from the stand as his side struggled to get in to their stride.
In the eighth minute Hoops' striker Samaras raced past Caley defender Grant Munro and in to the box but his low angled drive from 14 yards was blocked by the feet of Inverness keeper Fraser.
In the 20th minute a side-footed effort from the Greece striker was parried away to safety by Fraser at his right-hand post.
The restless Hoops fans were in no mood to cut their players any slack but there was generous applause in the 26th minute when McGeady's right-footed drive from 25 yards was saved by Fraser at the second attempt.
Moments later, Shunsuke Nakamura picked up a McDonald lay-off and skimmed a left-footed drive just past Fraser's post. Inverness were neat and tidy, if rather lightweight, and their first real effort of the game arrived in the 32nd minute when Douglas Imrie slipped a shot from 20 yards past the post.
Home defender Lee Naylor had a goalbound shot deflected past the post for a corner with five minutes remaining, before Samaras headed a Nakamura cross wide of the target. It was looking bleak for the home side.
Fraser had another save from McGeady, although less convincing as he dropped a cross-cum-shot before gathering.
But with seconds remaining McDonald latched on to a Nakamura free-kick from wide on the right to knock the ball in from close range for the opener. It was the last action of the first half and Parkhead breathed a huge sigh of relief.
The champions came out for the second half buoyed by their advantage and they immediately went in search of a second goal.
Caley right-back Ross Tokely almost headed a Nakamura free-kick into his own net in the 50th minute and two minutes later Samaras casually drove against the post from the edge of the box with Hoops' defender Andreas Hinkel knocking the rebound high over the bar.
Don Cowie's whipped-in free-kick from the left, which flew past Artur Boruc's far post, was Caley's reply.
Celtic's second goal came on the hour mark and was fashioned by their best player, McGeady.
The Republic of Ireland wide-man, who had been dancing down the wing all night, whipped in a cross from the left with his right foot and Samaras rose high to bullet a header from eight yards past the helpless Fraser.
But in the 70th minute Celtic put themselves under needless pressure when midfielder Brown gave possession away to Caley striker Niculae who controlled the ball before curling his shot past Boruc and in to the far corner.
The mood of the game changed in a instant.
Caley sensed they could perhaps steal a point but Fraser had to react quickly at his near post with eight minutes remaining to parry Brown's prodded shot from a Nakamura pass.
Caley went all out for the equaliser but failed to really trouble Boruc again.