Match ends, Dundee United 1, Celtic 4.
Leigh Griffiths scored his 50th and 51st goal for Celtic in a rout of beleaguered Dundee United at Tannadice.
The striker opened the scoring with a low drive midway through the first half.
Jozo Simunovic made it two soon after from a close-range header.
United threatened to make a game of it when Simon Murray made it 2-1 before half-time, but Griffiths scored the third before Kris Commons volleyed home a stunning fourth.
The win puts the champions six points clear of Aberdeen at the top, while United remain 11 points adrift at the bottom.
To make matters worse for United, some home supporters set off smoke bombs early in the evening, a mind-bending act of stupidity given that pyrotechnics have been such a talking point during the week.
Celtic were in the mood for this, no question. Even before Griffiths scored his first, they had chances.
When the striker took advantage of a slip from Gavin Gunning and rifled his shot under Eiji Kawashima you could have written off United there and then.
Mixu Paatelainen's team don't have a reputation for clawing themselves out of adversity. That was Griffiths' 50th for his club, a feat he marked by whipping off his jersey to reveal the magic number of goals he's scored for Celtic.
He got booked for his troubles. It hardly mattered because seven minutes later, Celtic's night got even better, and United's ever more desperate, when Kawashima came flying off his line to deal with a Celtic corner only to miss the ball by a veritable mile.
From his spot, roughly a yard from goal, Simunovic nodded Celtic into a handsome lead.
United rallied and created a fine team goal, which Murray finished off from John Souttar's through ball. The visitors became a little ragged in its aftermath, but as soon as the new half kicked-off they restored themselves to total dominance.
Griffiths' back-post effort beat an unconvincing Kawashima for the third only a few minutes into the second half. United were being over-run and when the fourth came it was swift and sweet.
Scott Fraser lost possession and Tom Rogic clipped his cross into Commons' air-space. The midfielder's finish was something special, a flying hitch-kick that sent the ball whizzing past Kawashima in a yellow blur.
United were denied a penalty when James Forrest handled in the box, but by then their players didn't even have the heart to raise much of a protest.
Celtic should have scored again, but it would have been mere decoration. They had long since played United out of the contest. Soon, you have to say, United will be played out of the league.
- 19GunningBooked at 47mins
- 4SouttarSubstituted forPatonat 82'minutes
- 15MurraySubstituted forErskineat 73'minutes
- 25RiskiSubstituted forDowat 64'minutes
- 63TierneySubstituted forIzaguirreat 78'minutes
- 18RogicSubstituted forForrestat 60'minutes
- 14ArmstrongSubstituted forAllanat 69'minutes
- 9GriffithsBooked at 22mins
- Bobby Madden
- Shots on Target
Second Half ends, Dundee United 1, Celtic 4.
Scott Fraser (Dundee United) wins a free kick in the attacking half.
Foul by Callum McGregor (Celtic).
Foul by Jozo Simunovic (Celtic).
Scott Fraser (Dundee United) wins a free kick on the right wing.
Attempt saved. Scott Fraser (Dundee United) left footed shot from outside the box is saved in the centre of the goal.
Attempt saved. Leigh Griffiths (Celtic) left footed shot from outside the box is saved in the bottom right corner.
Corner, Dundee United. Conceded by Jozo Simunovic.
Scott Allan (Celtic) wins a free kick in the attacking half.
Foul by John Rankin (Dundee United).
Attempt missed. Kris Commons (Celtic) right footed shot from the centre of the box is close, but misses to the left.
Foul by Mikael Lustig (Celtic).
Paul Dixon (Dundee United) wins a free kick in the defensive half.
Attempt missed. Blair Spittal (Dundee United) right footed shot from the right side of the box misses to the right.
Foul by James Forrest (Celtic).
Ryan McGowan (Dundee United) wins a free kick in the defensive half.
Corner, Dundee United. Conceded by Mikael Lustig.
Foul by Mikael Lustig (Celtic).
Gavin Gunning (Dundee United) wins a free kick in the defensive half.