A stunning first-half performance by Celtic earned them a comfortable 3-0 win at St Johnstone and maintained their five-point lead at the top of the Scottish Premiership.

Neil Lennon's side preserved the gap cleaved open following Rangers' weekend defeat with three goals in 20 minutes.

Olivier Ntcham headed the visitors ahead, James Forrest doubled the lead with an angled strike, and Leigh Griffiths volleyed in his third in four games to complete the scoring after just 26 minutes.

Rangers' win over Ross County means Celtic's advantage at the summit remains at five, having played a game more.

St Johnstone, meanwhile, remain in eighth place, level on points with Kilmarnock and with a game in hand.

Celtic better in every aspect

St Johnstone's recent woes against Celtic have been well documented. They were beaten 7-0 on the opening day of the season. They had conceded 27 goals since they last scored one against them. In fact, since the Perth side's last strike in August 2017, Celtic have won seven trophies.

But neither Tommy Wright nor Neil Lennon were paying much attention to those stats. More encouraging for the hosts was the one loss in their last eight games, and just three goals conceded in that time.

For that reason, Lennon said he anticipated a tough game where his side would have to be at their best. Well, they were certainly at their best. They just didn't have to be.

St Johnstone's five-man defence were half-asleep as the game kicked off - and if anything, seemed to drift further into their slumber - and Celtic were able to cut through them with ease.

The strike duo of Griffiths and Odsonne Edouard exhibited promising link-up play within the first minute and Celtic's wing-backs - Forrest and the impressive Greg Taylor - pegged their counterparts back with relentless pressure. When they got hold of the ball, the quality of delivery was outstanding.

By the time Ntcham's headed home inside six minutes from Forrest's cross - his 18th assist of the season - they had already had three shots, one of which Griffiths should have buried from a Taylor cross.

It's no exaggeration to say that Celtic could have been four or five goals ahead inside 10 minutes. As it happened, they had to wait until the 20th minute to double their lead.

Scott Tanser did his best to allow Forrest the freedom of McDiarmid Park, before the winger shifted the ball on to his right foot and slotted the ball across Zander Clark and into the far corner.

Six minutes later, Griffiths made it three, coolly slotting in a volley from a Taylor cross. In the aftermath, Clark then had a juice carton thrown in his direction from the Celtic support behind his goal.

By the time of that goal, Celtic had already taken 11 shots - just under a shot every two minutes, and none were speculative.

Such was the difference in quality between the two sides in the opening stages, it probably would have been a fair suggestion to ask the referee to mix the teams up for the second-half.

But that third goal killed the match not only as a contest, but as a spectacle as St Johnstone employed damage limitation tactics, presumably desperate to avoid yet another drubbing.

As for Celtic, you can understand them wanting to take it easy with the game already wrapped up. The win was the the latest game of a hectic schedule in which they play nine times over the next 30 days.

Though they allowed St Johnstone a foothold in the game in the second half, Celtic's display in the opening half-hour was as complete as you'll see.

They zipped the ball around the pitch at a ferocious tempo, hassled, harried, kept a second consecutive clean sheet having conceded in their previous five games, and showed a finishing touch when it mattered.

An impressive performance ahead of a testing run.

Man of the match - James Forrest

BBC Sport Scotland's Martin Dowden at McDiarmid Park

Given Celtic's start, you could have picked out any of their offensive players as star man. Threat was coming from everywhere with Edouard and Griffiths combining well as they pinned St Johnstone in and created chance after chance.

They were ably supported by the likes of Callum McGregor, Ntcham, Taylor and Forrest, who seems to love playing against this opposition.

It was his delivery which created the opener. An inch perfect cross that allowed Ntcham to power home without breaking stride. Forrest's composure and execution were evident again when he created a gap and smashed home an angled second to end the contest.

One of the major improvements in Forrest's game over the years has been that final ball and ability to finish. It gave Celtic the platform for victory tonight among a host of strong performances.

'We had to show character' - reaction

St Johnstone defenders were statuesque - Wright

St Johnstone manager Tommy Wright: "We didn't start the game well - passive, defended too deep, allowed too many crosses, didn't put a tackle in, didn't win a header in our own box.

"They have then got to show character because having been beaten 7-0 we didn't want that to happen again, and they did. Second half, we got up the pitch a bit and worked their keeper a couple of times."

Celtic manager Neil Lennon: "The first half was outstanding, the fluidity of the team and the chances we created, the attitude, and the overall quality of football and pace we played at was breathtaking.

"We had to change the shape because Jozo had a knee problem. He has gone above and beyond the call of duty. He couldn't carry on so we had to changed the shape, which probably stopped the natural flow we had."

One of the best of the season - Celtic's Lennon