Gary Hooper was the hero again as Celtic moved 12 points clear at the top of the Scottish Premier League with a comfortable victory over Dundee United.
Hooper put his side in front, finishing a superb counter-attack in a hectic opening period.
Victor Wanyama made it two with a close-range header and Hooper killed United off with a deft flick past Radoslaw Cierzniak.
Substitute Scott Brown rounded off the scoring with a left-foot curler.
Other than an utterly breathless opening 10 minutes in which both sides created a number of clear-cut chances, United rarely threatened to take anything from the game.
Celtic barely moved out of cruise control despite notching four goals for the second time in four days, with Hooper grabbing a double again and showing just why
Prior to him getting off the mark though, Georgios Samaras should have hit the target with a header before United's Gary Mackay-Steven slipped a shot past Lukasz Zaluska but also past his right-hand post.
Hooper put a couple of efforts off-target, with Willo Flood flashing a shot wide at the other end and Zaluska got lucky when his attempted clearance cannoned off Jon Daly's back before bouncing precariously close to goal.
So when the deadlock was broken after 18 minutes, the only surprise was that it had taken that long.
When it came, it was a thing of beauty. A United corner kick was knocked out of the Celtic box allowing Lassad Nouioui to break at pace over the halfway line.
With only two defenders back, his superb ball into the path of Samaras was matched by the Greek's first-time pass to the unmarked Hooper, who slotted under the diving Cierzniak.
The game hit something of a lull after the goal, but Celtic Park came to life again in the 34th minute.
Gavin Gunning did well to block Lassad's shot away for a corner, but when it was laid back to Mikael Lustig, the Swede swung the ball to the back post where Wanyama headed across Cierzniak and into the far corner of the net.
Wanyama almost had a second just before half-time when he headed a Mulgrew corner off the frame of the goal, with United only just scrambling the rebound away as Celtic exerted their authority on the match.
United clearly needed the next goal if they were to make a game of it, and they almost had it on the hour-mark.
Barry Douglas swung a corner outwards from the left and Daly met it powerfully, only to see his headed effort swept off the line.
Cierzniak saved from Samaras as the game began to become stretched but United looked incapable of stepping up their efforts and they were killed off altogether when Hooper scored his second - a lovely near-post flick from Samaras's low cross.
Celtic carved out a fourth through their captain, who picked the ball up from Hooper, turned the ball onto his left foot and curled a shot high past Cierzniak.
The scoreline was not a flattering one as Celtic again highlighted the disparity between themselves and the competition.