Leigh Griffiths second hat-trick in 11 days spurred Celtic to a 3-0 win away at Dundee United on Sunday and ever closer to the Scottish Premiership title.

Robbie Muirhead came close to opening the scoring for United in a goalless first-half before Griffiths fired home the opener just over 90 seconds after the restart.

United 'keeper Radoslaw Cierzniak made superb saves to deny Kris Commons and Stefan Johansen before he was beaten for a second time with a close range finish from Griffiths.

Former United player Gary Mackay-Steven hit the crossbar before earning Celtic an 84th minute penalty that Griffiths expertly despatched to complete his hat-trick - coming hot on the heels of the treble he scored in the 4-1 win over Kilmarnock.

Celtic are now eight points clear of Aberdeen, who won 2-1 away to Inverness on Saturday, with just four matches remaining.

The Hoops made three changes for the trip to Tannadice with Adam Matthews, Commons and Johansen returning to the starting line-up while Mackay-Steven had to settle for a place on the bench.

Muirhead, in his first start since signing for United from Kilmarnock in January, came close to opening the scoring in the 21st minute with a first-time left-foot shot from 20 yards that Craig Gordon did well to tip over.

Cierzniak had to be alert in the United goal to turn a deflected Commons shot round the post before blocking a snatched shot from Virgil van Dijk.

It took Celtic just 90 seconds of the second half to open the scoring. A good passing move ended with Johansen laying the ball off for Griffiths, who took a touch before rifling an angled shot into the bottom left-hand corner.

Cierzniak stopped Celtic from immediately doubling their lead when Commons connected with Johansen's cross to power a header towards goal, but the 'keeper made a tremendous save from point-blank range.

The Polish keeper then made another fabulous stop to keep out a stinging strike from Johansen from 20 yards.

However, he could do nothing to prevent Griffiths grabbing his second of the game in the 65th minute.

Van Dijk headed Mackay-Steven's corner against the post but the Scotland striker was in the right place to knock the ball over the line from a couple of yards out.

Mackay-Steven came within inches of scoring when his powerful strike from the edge of the box smacked off the crossbar before he earned Celtic an 83rd minute penalty when John Rankin hauled him down as he burst into the box at pace.

Griffiths then sent Ciernziak the wrong way from the penalty spot to seal his hat-trick.