Celtic produced an outstanding second-half performance to blow away a hitherto resolute Ross County.
The visitors missed two golden opportunities in a goalless first period and were punished ruthlessly after the break.
Scott Brown broke their resistance and Gary Hooper headed in a quick second.
Hooper added the third goal, again with his head, before James Forrest came off the bench and marked his comeback from injury with a fine solo effort.
The victory stretches Celtic's lead at the top of the Scottish Premier League to five points with a game in hand over Inverness Caledonian Thistle.
Forrest celebrates scoring his first goal of the season
But their performance in either half could hardly have been more contrasting, with Neil Lennon presumably having something to say at the interval about an indecisive display in the opening 45 minutes.
That said, Celtic were utterly dominant during the opening stages, with Mark Brown saving from a Lassad header and a Charlie Mulgrew shot before also reacting quickly to palm away a header from Hooper.
County began to come to terms with Celtic's narrow set-up, the midfield three and front three all playing in largely central areas, and created a couple of openings of their own, the most threatening of which ended with Rocco Quinn sending a fierce drive from outside the box just over Fraser Forster's bar.
Hooper, playing behind Samaras and Lassad, nonetheless looked Celtic's greatest threat and had two goal-bound shots blocked, first by Mihael Kovacevic and then Marc Fitzpatrick.
The home fans chanted "Bring on the Juve", but the intensity of their Champions League performances was, not for the first time this season, lacking.
Kayal, playing as industriously as ever, did bring a decent save out of Brown a few minutes before the break, but Celtic could just as easily have found themselves behind at the interval.
Quinn tamely passed the ball into the arms of Forster with the goal at his mercy and then Alex Cooper fired straight at the goalkeeper.
County were made to regret those misses not two minutes into the second half as Hooper slid the ball through for the onrushing Brown, who, from the angle of the six-yard box, fired under his namesake in the visitors' goal.
Six minutes later, Hooper had a goal of his own as he glanced a Lassad cross past the keeper from all of six yards.
Those goals knocked the fight out of County and, by the time Celtic struck again, the home side were cruising.
The third goal came from a Mulgrew corner, which was headed down by Victor Wanyama and nodded into the net by Hooper once more.
That came in 64 minutes and it was soon followed by a fourth - a wonderful run and finish by the substitute, Forrest, marking his first appearance since October with his first goal of the season.
Hooper almost had his hat-trick with five minutes remaining, but his close-range lunge forced the ball against the woodwork.
Shortly afterwards, had a back-flick wound up in the net rather than in the arms of Brown, it would have been a fitting end to a splendid Celtic move.
Nonetheless, Hooper and his team-mates had already done more than enough to merit a convincing victory.
Substitution Gary Glen replaces Stuart Kettlewell.
Tony Watt challenges Paul Lawson unfairly and gives away a free kick. Free kick taken by Scott Boyd.
Tony Watt produces a right-footed shot from long range which goes wide right of the goal.
Gary Hooper takes a shot.
Substitution John Herron is brought on as a substitute for Georgios Samaras.
Corner taken left-footed by Iain Vigurs, clearance by Efe Ambrose.
Inswinging corner taken right-footed by Richard Brittain played to the near post, Georgios Samaras manages to make a clearance.
Substitution Rocco Quinn leaves the field to be replaced by Paul Lawson.
Substitution (Celtic) makes a substitution, with Tony Watt coming on for Lassad Nouioui.
Scott Boyd gives away a free kick for an unfair challenge on Georgios Samaras. Free kick taken by Charlie Mulgrew.
Booking Kelvin Wilson receives a caution.
Kelvin Wilson challenges Iain Vigurs unfairly and gives away a free kick. Indirect free kick taken by Richard Brittain.
Assist by Gary Hooper.
69:34 Goal scored
Goal! - James Forrest - Celtic 4 - 0 Ross Co James Forrest fires in a goal from inside the box to the bottom right corner of the goal. Celtic 4-0 Ross County.
Booking Grant Munro goes into the book.
Booking The referee shows Richard Brittain a yellow card for unsporting behaviour.
Richard Brittain challenges Gary Hooper unfairly and gives away a free kick. Indirect free kick taken by Charlie Mulgrew.
The assist for the goal came from Victor Wanyama.
63:06 Goal scored
Goal! - Gary Hooper - Celtic 3 - 0 Ross Co Gary Hooper finds the back of the net with a headed goal from inside the box. Celtic 3-0 Ross County.
Inswinging corner taken from the right by-line by Charlie Mulgrew,
Booking The referee shows Stuart Kettlewell a yellow card for unsporting behaviour.
Inswinging corner taken by Charlie Mulgrew.
Substitution James Forrest replaces Beram Kayal.
Free kick awarded for a foul by Stuart Kettlewell on Beram Kayal. Charlie Mulgrew restarts play with the free kick.
Effort on goal by Rocco Quinn from deep inside the penalty area misses to the right of the target.
Substitution Mark Corcoran replaces Alex Cooper.
Lassad Nouioui provided the assist for the goal.
52:10 Goal scored
Goal! - Gary Hooper - Celtic 2 - 0 Ross Co Gary Hooper finds the net with a headed goal from inside the six-yard box. Celtic 2-0 Ross County.
Rocco Quinn is flagged offside by the assistant referee. Fraser Forster takes the free kick.
Rocco Quinn gives away a free kick for an unfair challenge on Emilio Izaguirre. Victor Wanyama takes the indirect free kick.
Mihael Kovacevic takes a shot. Save by Fraser Forster.
Gary Hooper provided the assist for the goal.
45:56 Goal scored
Goal! - Scott Brown - Celtic 1 - 0 Ross Co Goal scored by Scott Brown from inside the box to the bottom left corner of the goal. Celtic 1-0 Ross County.
The referee blows his whistle to start the second half.
45:00 +2:52 Half time
Half Time The referee calls an end to the first half.
Alex Cooper takes a shot. Save by Fraser Forster. Corner taken right-footed by Richard Brittain from the left by-line to the near post, clearance made by Efe Ambrose.
Scott Brown fouled by Marc Fitzpatrick, the ref awards a free kick. Efe Ambrose restarts play with the free kick.
Rocco Quinn takes a shot. Save by Mark Brown.
Beram Kayal has a drilled shot. Save made by Mark Brown.
The ball is sent over by Lassad Nouioui, Grant Munro manages to make a clearance.
Emilio Izaguirre sends in a cross.
Stuart Kettlewell challenges Victor Wanyama unfairly and gives away a free kick. Free kick taken by Victor Wanyama.
Corner taken by Charlie Mulgrew from the right by-line, Grant Munro manages to make a clearance.
Effort from 20 yards by Alex Cooper. Save by Fraser Forster.
Shot by Lassad Nouioui. Save made by Mark Brown.
Foul by Alex Cooper on Georgios Samaras, free kick awarded. Victor Wanyama takes the indirect free kick.
Beram Kayal has a shot on goal from outside the area which misses left.
Emilio Izaguirre crosses the ball.
Unfair challenge on Emilio Izaguirre by Alex Cooper results in a free kick. Charlie Mulgrew takes the free kick.
A cross is delivered by Emilio Izaguirre, Richard Brittain makes a clearance.
Scott Brown is ruled offside. Mark Brown restarts play with the free kick.
Inswinging corner taken from the right by-line by Charlie Mulgrew, clearance made by Grant Munro.
Stuart Kettlewell concedes a free kick for a foul on Georgios Samaras. Charlie Mulgrew takes the indirect free kick.
Foul by Mihael Kovacevic on Georgios Samaras, free kick awarded. Indirect free kick taken by Victor Wanyama, Rocco Quinn produces a right-footed shot from just outside the box that misses to the right of the net.
Alex Cooper fouled by Victor Wanyama, the ref awards a free kick. Iain Vigurs takes the indirect free kick.
Beram Kayal takes a shot.
Stuart Kettlewell takes a shot.
Headed cross/shot by Gary Hooper, save by Mark Brown.
Victor Wanyama concedes a free kick for a foul on Mihael Kovacevic. Mark Brown takes the indirect free kick.
Foul by Stuart Kettlewell on Beram Kayal, free kick awarded. Free kick taken by Beram Kayal.
Charlie Mulgrew takes a shot. Save by Mark Brown.
Scott Boyd challenges Beram Kayal unfairly and gives away a free kick. Free kick taken by Georgios Samaras.
Beram Kayal gives away a free kick for an unfair challenge on Richard Brittain. Free kick taken by Mark Brown.
Emilio Izaguirre sends in a cross, Lassad Nouioui takes a shot. Save by Mark Brown.
The ball is sent over by Georgios Samaras, Richard Brittain makes a clearance.
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