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.
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.