Dundee United 1-4 Celtic: Leigh Griffiths double downs United

Celtic moved six points clear of Aberdeen at the top of the Scottish Premiership as in-form striker Leigh Griffiths went past the 50-goal landmark with a double in a comprehensive 4-1 victory against Dundee United.

The bottom-placed side had won only two league games all season and basic defensive errors cost them dear as Griffiths and Jozo Simunovic put Celtic in early control.

A fine Simon Murray strike gave the hosts hope and they had other chances, but were ruthlessly punished by Griffiths and Kris Commons before the hour as the confidence drained from Mixu Paatelainen's struggling side, who remain 11 points adrift of Kilmarnock.  

Scott Fraser had blazed well over the top after a long-bursting surge while Stuart Armstrong failed to hit the target from 12 yards at the other end.

Commons drilled a skidding drive narrowly wide from 22 yards and Armstrong also went close with a curling effort from the angle.

Griffiths reached his half century for Celtic after Tom Rogic's pass had deflected kindly into his path and last man Gavin Gunning lost his footing; the striker needed no second invitation as he scurried into the area and fired through goalkeeper Eiji Kawashima's legs (21).

Simunovic (27) then rose unchallenged to meet Common's free-kick, with Kawashima grasping at thin air, and the neutral might have feared for United at this stage.

But they pulled a goal back after a fine build-up led to a perfectly weighted through ball from John Souttar and a deft Murray (31) flick that gave Craig Gordon no chance.

Kawashima was at full stretch to beat away a thumping Commons free-kick before Murray's touch let him down as he burst into the box looking to capitalise on defensive uncertainty. Moments later, Mikael Lustig's cross at the other end was swept in at the far post by an unmarked Griffiths (48).

United were on the ropes and the overworked Kawashima made two good saves to deny Griffiths and Callum McGregor but was powerless when Fraser was dispossessed cheaply and Commons (56) claimed one for the scrapbook with a sweet scissor kick from Armstrong's clipped delivery.

Commons had a goal chalked off and if United wanted any confirmation that it was not to be their night it came when substitute James Forrest appeared to control the ball with his hand in his own area - and referee Bobby Madden waved play on. 

Griffiths flicked over the bar from six yards and Commons missed a tap in as Celtic cruised home, the only black spot for the visitors coming when they lost the excellent Kieran Tierney, seemingly with a recurrence of a shoulder injury.