Second-half goals from James Forrest and Stefan Johansen earned Scottish Premiership leaders Celtic a 2-0 win over bottom-placed St Mirren this evening.

Forrest broke the deadlock on 64 minutes before winning a penalty which Johansen converted to secure three points which send Celtic eight clear at the top.

The vast gap between the two sides in the table was not too evident in a goalless opening 45 minutes, although it was Celtic who started on the front foot as Anthony Stokes shot wide on the turn and Kris Commons tested Mark Ridgers at his near post.

The Scotland international then should have given the visitors the lead in Paisley when he fired straight at Ridgers from 12 yards out following a Stuart Armstrong cross.

However, St Mirren grew into the game as the half went on and Kieran Sadlier did well to provide Stevie Mallan with a headed opportunity which he sent into the arms of Craig Gordon, before working the visiting goalkeeper himself from distance.

The hosts also had a strong shout for a penalty turned down after Mallan was brought down in the box by Adam Matthews, and their failure to make the most of their period on top was always going to be costly against the champions.

After Commons and Stokes had wasted further chances at the start of the second half, Matthews ran onto a Scott Brown through-ball to cross for Forrest to side-foot into the net and put Ronny Deila's side ahead.

Having been kept shackled by Saints full-back Jeroen Tesselaar for much of the opening hour, Forrest lost his man again on 79 minutes to unleash a shot which was adjudged to have been blocked by Viktor Genev's hand.

Johansen stepped up to convert his 12th goal of the season from the spot, securing Celtic a ninth win in 10 league games.