The game was goalless at half-time – by which time United had been reduced to 10 men after Robbie Neilson had followed up a foul on Georgios Samaras – for which he was cautioned – with a flailing arm into the Greek’s face to earn a straight red card.
That was the turning point the afternoon and once Celtic got in front through a tidy finish from Joe Ledley, the proceedings steadily shifted in their favour. Samaras added to an eventful outing by heading a Charlie Mulgrew free-kick past Dusan Pernis from close range and there was no way back for Peter Houston’s players when Ledley released Anthony Stokes for his 20th goal of the season.
Stokes had earlier struck the crossbar when the entire goal was open to him from a James Forrest cutback to the loudly expressed amusement of the Celtic fans, but he had long since been forgiven by the time Scott Brown buried a penalty kick awarded when Samaras was tripped by Sean Dillon in the dying seconds.
Beforehand, a tetchy Neil Lennon explained why Celtic had not staged their customary pre-match media briefing on Friday. “We decided not to hold a press conference this week because of all the nonsense going on elsewhere – people accusing our club of trying to put people out of work at Rangers and telling lies about agreements,” said the Hoops manager.
“There’s a lot of muckraking amongst some hacks. It’s in the hands of our legal team and it’s probably best not to talk about it.
“We want to get our heads down and we want to talk about football. A lot of media outlets will be disappointed because we won’t be speaking to them.
“We’ll do our speaking through the club. I’m angry but I’ll deal with it in my own way.”
After such a declaration of intent, Celtic proved oddly inarticulate in a drab first half, in which the tactical contest was edged by United until Neilson’s flying elbow altered the balance of play. Samaras, in his familiar detached fashion, seemed quite uninterested in checking back to counter the thrusts of Willo Flood along the United right, a piece of negligence that encouraged Dillon to get in on the act.
Lennon’s response was to withdraw Victor Wanyama to central defence, push Mulgrew out to left-back and switch Ledley into midfield. The switch paid off but not before Fraser Forster had been forced to make an outstanding reflex save from a venomous Johnny Russell effort.
The breakthrough, eight minutes after the break, came precisely because of Ledley’s advanced role, when he broke from midfield in support of a Stokes break and was in perfect position to beat Pernis with a tidy shot from six yards. At 1-0, though, nothing could be taken for granted and if Milos Lacny – who had replaced the injured Gavin Gunning – had been only a touch more assertive with a left-foot drive inside the Celtic box he would have levelled the score instead of pushing his attempt narrowly wide.
This profligacy was punished almost immediately when Flood fouled Stokes for the Mulgrew free-kick from which Samaras scored. Celtic’s third was a replay of their first, except with the roles reversed so that Ledley set up Stokes for a finish that gave the Dubliner his 20th goal of the season.
Samaras completed an eventful afternoon when he was barged by Dillon inside the box. Pernis guessed the direction of Brown’s penalty kick but seemed to dive over the ball as it crossed the line.
“We were disjointed in the first half and we have to look at how that happened,” said Lennon.
“We won’t win a treble if we do that too often, but by the end I thought we were pretty convincing and now we turn our attention to next week’s League Cup final against Kilmarnock.”
Dundee United (4-4-2): Pernis; Neilson, Dillon, Gunning (Lacny 58), Dixon; Flood (Armstrong 78), Robertson, Rankin, Mackay-Steven (Kenneth 30); Daly, Russell. Subs: Banks (g), Ryan. Booked: Neilson.Sent off: Neilson.
Celtic (4-4-2): Forster (Zaluska 87); Matthews, Rogne, Mulgrew, Ledley; Forrest, Brown, Wanyama, Samaras; Hooper (McCourt 80), Stokes (Commons 87). Subs: Wilson, Cha.
Referee: I Brines.