Celtic extended their lead at the top of the Scottish Premiership to six points as they held off a late comeback to secure a 2-1 victory over St Johnstone at McDiarmid Park.

The Hoops made what is fast becoming a trademark explosive start when they took just 35 seconds to breach the St Johnstone defence as Leigh Griffiths fired past 'keeper Alan Mannus.

The Scotland international then spurned three chances to add to his tally as Mannus kept him at bay before he produced an excellent save to stop Gary Mackay-Steven.

However, the 'keeper couldn't do anything to stop Celtic from increasing their lead in the 52nd minute when Stefan Johansen showed great skill to finish a well-executed move.

The Scottish champions appeared to be strolling to a comfortable victory before Michael O'Halloran fired past Craig Gordon in the 72nd minute to reduce the deficit as Celtic conceded a goal for the first time in 816 minutes of football.

Celtic had 'keeper Craig Gordon to thank with two late superb saves as the Hoops held on to secure their eighth victory in a row before they head into Thursday's crucial Europa League last 32 clash with Italian giants Inter Milan.

"I think the players worked hard for 90 minutes and at 2-0 it seemed quite comfortable," Celtic manager Ronny Deila said.

"Then we conceded a goal and everything turned around. They were very aggressive and direct and we needed to defend well in the end."

St Johnstone manager Tommy Wright picked the positives from his players' performance.

"Celtic had a lot of chances in the game but you've always got a chance and it was a tremendous double save from Gordon that probably denies us a point," Wright said.

"I thought, particularly in the second half, we played extremely well against them and I'm proud of the players and how they responded."

Celtic had needed just 38 seconds to open the scoring against Partick Thistle on Wednesday and made a similar quick-fire start in Perth. Griffiths was the only change from the midweek win and the Scottish striker made an instant impact when he netted after 35 seconds.

Nir Bitton's long-ball from the Celtic half split the St Johnstone defence and Griffiths nipped in to stroke the ball past Mannus.

The striker had a chance for a second minutes later when Virgil van Dijk's downward header from a corner came off his knee but Mannus snuffed out the danger.

Chris Kane headed just wide from O'Halloran's cross in a rare St Johnstone chance before Johansen's excellent through ball released Griffiths for another effort but 'keeper Mannus stuck out a foot to keep out his effort.

The St Johnstone 'keeper was the hero again when he stuck out a hand to palm away an angled shot from Griffiths moments later after he was set up by Mackay-Steven.

St Johnstone managed an effort on target shortly afterwards through a Steven Anderson header before Mannus produced a finger-tip save to keep a ferocious 20-yard strike from Mackay-Steven making its way into the top left-hand corner.

The Hoops got the second goal their dominance deserved in the 52nd minute with a superb strike from Johansen. Griffiths headed Stuart Armstrong's lofted pass into the path of the Norwegian midfielder who juggled the ball superbly before lashing it beyond the helpless Mannus.

Out of nowhere St Johnstone managed to haul themselves back into the match through O'Halloran. Celtic stopper Gordon blocked Kane's shot from Brian Easton's cross but the rebound fell to O'Halloran who expertly rifled it into the roof of the net.

Only an incredible double save from Gordon kept Celtic in front. The 'keeper made a one-handed save to stop Brian Graham's header before he managed to push Dave Mackay's close-range volleyed rebound over the bar.