This powerful, emphatic result at Tynecastle added to a growing body of evidence that there aren't only two different Celtics on show this season, but three.
There has been endless discussion about the huge difference between their performances in Champions League ties and the often humdrum efforts they produce in low key Clydesdale Bank Premier League games. But there is another side to them. In what Neil Lennon's side are entitled to regard as the tougher domestic challenges of the campaign, they deliver far sharper, more disciplined displays. It is as if they know that by handling the bigger occasions they can buy themselves breathing space for the bread-and-butter games.
If their supporters have been disgruntled by what they've witnessed at Celtic Park, those who follow them away from home have enjoyed regular gratification. They have now scored 21 away goals in the league compared to only seven at home and, in general, there has been a greater sense of intensity and control about their displays on the road.
Hearts at Tynecastle should always be one of the cauldrons of the Scottish game but, for now, Celtic have the measure of this fixture. The last time they were here, they won 4-0 and they did it again this time. Hibernian are now second, but what was only Celtic's second win in six league games consolidated their lead in the Clydesdale Bank Scottish Premier League. Scottish Cup and Champions League assignments against Arbroath and Spartak Moscow await over the next six days.
Celtic blitzed Hearts, burying them with three goals in the first half hour. Lassad, Mikael Lustig and a Ryan Stevenson own goal finished things before the game was out of its infancy while Gary Hooper embellished the rout with a fourth at the end. Perversely Celtic's man of the match was Fraser Forster, who kept out whatever Hearts threw at him, including a penalty. Celtic needed their excellent goalkeeper to preserve a clean sheet, but a comfortable victory was never in question.
Never mind that Hearts' defending was poor, the finishing from Celtic was crisp and clinical. Kris Commons swung over a cross and Lassad connected with a sweet volley to finish low inside the post. The Tunisian was involved for the second, too, combining with Lustig before the right-back drove on to score after Darren Barr could only half clear a cross. When Charlie Mulgrew then flashed a ball over from the other side which struck Stevenson and cannoned in to his own net, some of the Tynecastle faithful had clearly seen enough and headed for the exits.
Celtic had scored in 10, 22 and 30 minutes: at that rate this young and inexperienced Hearts team were heading for an awful beating. Their willingness to keep working hard spared them any real humiliation and conceding only once in the remaining hour almost felt like a mercy. As a match, it was untidy, rushed and scrappy – too many fouls and fractured moves – but 15,264 found it compelling. The two sets of fans goaded each other from start to finish but Hearts had no real comeback to the punishment being inflicted on their team.
Neil Lennon's reaction to the weekend defeat by Inverness Caledonian Thistle was to replace Georgios Samaras, Adam Matthews and Tony Watt with Lassad, Joe Ledley and Kelvin Wilson. Victor Wanyama was at the base of a midfield diamond with Ledley left, Biram Kayal right and Commons at the head of it behind Lassad and Gary Hooper. Commons, Wanyama and Lustig had fine games. Hearts's 4-5-1 shape allowed them plenty of possession in the Celtic half, but while they had guts and strength, they lacked creativity or a sense of threat, and they were consistently picked off on the counter-attack.
Hearts were so vulnerable at the back that it undermined all the efforts they made to press and attack Celtic. They had their chances, but there was none of the deadliness on show at the other end, nor the defensive frailty.
When Stevenson's free- kick found Callum Paterson ghosting in behind the back four, he failed to connect with a header in the six-yard box. A ferocious Stevenson drive was brilliantly saved by Forster, who reacted instantly to also block Marius Zaliukas' attempt from the rebound.
Forster was outstanding. Hearts' young left-back, Kevin McHattie fizzed a free-kick which skipped up at him early in the second half and he blocked that too. Hearts had a good early claim for a penalty when the ball struck Lassad's arm but even when they got one two minutes from the end, it came to nought. Wilson fouled Stevenson but Forster flung himself to the right to keep out Zaliukas' kick.
It was to the Hearts fans' credit that they persisted in making a racket, but they fled the scene when the fourth went in. MacDonald had saved a late one-on-one chance for Commons but, moments later, Mulgrew crossed for Hooper to finish. It was all too easy.