FAMILIARITY breeds contentment for Celtic.

A third meeting with Dundee United in 11 days could have presented its own difficulties for Ronny Deila and his players but there would be no repetitive strain.

Following the draw in the original William Hill Scottish Cup tie at Tannadice and then the League Cup final victory at Hampden, this performance would prove to be the most comfortable of the lot, Celtic eventually winning by four clear goals. Their reward is a semi-final against Inverness Caledonian Thistle next month, Celtic another step closer to delivering a treble in Deila's maiden campaign. United, who barely threatened in an attacking sense, are back in Glasgow for a fourth successive match against Celtic on Saturday.

With former players Stuart Armstrong and Gary Mackay-Steven also available for that one, it is not a journey Jackie McNamara and his players will look forward to with any great relish. They have still not won at Celtic Park for 23 years and rarely looked like doing so on this occasion.

A game that had passed largely without incident exploded in the closing minutes. It was quite a fracas and made a mockery of the insistence on the part of both sides that there had been no lingering ill-feeling following the original tie that had been filled with red cards, heavy tackles and other controversial moments.

Anthony Stokes was the first to go three minutes from time, following a collision with Paul Paton. The Irishman seemed aggrieved by the decision and motioned to referee Calum Murray that he had taken an elbow for his troubles, displaying a burst lip. That wasn't the end of it. Two minutes later and United's Ryan McGowan was traipsing up the tunnel for a heavy challenge on Liam Henderson. That sparked a melee near the United goal line, with John Guidetti and Emilio Izaguirre both picking up bookings. A minute later and there was another yellow card, this time for John Rankin. Saturday's meeting, the fourth and final instalment of this particular story, could well be another feisty one.

United had been bolstered by the return of "the best player in Scotland on his day", the somewhat lofty build-up given to Nadir Ciftci by his manager ahead of the striker's return from suspension. The Turk had been missed in the cup final but even with him restored to the side United rarely posed a threat, aside from a spell at the start of the second half, spending large chunks of the contest on the back foot trying to quell Celtic's constant stream of attacks.

Ciftci had one long-range effort in the first half that Gordon saved fairly comfortably, and another from a tighter angle early in the second that the goalkeeper pushed away as if guddling for fish. When a rare United cross from McGowan squirmed out of the goalkeeper's grasp Ciftci seemed so surprised that he couldn't capitalise. He was marginally more effective when pushed wide left but this wasn't the kind of impact United had been hoping for from their talisman.

McNamara had conceded that Ciftci could be "temperamental" at times, something that Scott Brown put to the test within the opening six seconds with an early nibble at his ankles. Given the last time the pair met Ciftci had kicked Brown on the head and got away with it then perhaps it was the least the United player should have expected. A difficult night for the striker ended with a late booking.

United had felt aggrieved with some of the decisions made at Hampden, in particular the non-award of a first-half penalty, but any thoughts of a refereeing conspiracy against them were surely obliterated within the opening minute when a massive call went in their favour. Kris Commons sent Leigh Griffiths scampering in on goal, Radoslaw Cierzniak rushed out to meet him just outside the penalty box but got only the man not the ball. Griffiths embellished the tumble but it was undoubtedly a foul, the only remaining issue what colour the card would be. Cierzniak looked up and was a relieved man to see Calum Murray brandishing a yellow and not a red.

The goalkeeper wouldn't have it all his own way, of course, and after 17 minutes he was fishing the ball out of his net. It was a poor goal to concede from United's point of view, Stokes plopping a free kick straight on to Jason Denayer's head. The Belgian was never likely to miss from about eight yards.

Celtic looked in control after that although their second goal did come against the run of play, after United belatedly bared their teeth. Brown was the creator, bursting forward before sending in an enticing cross that Griffiths volleyed past Cierzniak. Griffiths' timing was perfect in more ways than one - it would be his last involvement in the match, removed for Guidetti immediately after scoring.

That looked like that although Celtic continued to pursue the third goal that had eluded them at Hampden. Stokes fired in a shot from distance that the goalkeeper repelled, and Commons dawdled and lost control after the Irishman had picked him out. Moments later, however, and Commons had his goal, working a 1-2 with Guidetti before chipping a neat finish over Cierzniak. After the red mist had settled, Celtic still had enough about them to score again, Denayer laying it on a plate for Virgil van Dijk to tap in from a matter of yards.