Celtic atoned for Saturday's home loss to Inverness in the most ruthless of styles. Within 30 first-half minutes, three points had been secured against Hearts in Edinburgh.
This was clinical stuff from Neil Lennon's team, and the perfect response to the Celtic manager's complaints about inconsistent domestic form. For all Celtic's occasional troubles, they remain clear at the summit of the Scottish Premier League. Here, Celtic were at their uncompromising best.
Hearts have played worse this season and won; they continue to lack bite in front of goal, however, which will be exposed against opposition of Celtic's calibre.
"I have told the players I don't want to keep looking for a reaction, I want us to be consistent," Lennon said. "I know we are capable of that kind of performance."
Hearts' biggest battles at present are being fought off the field, with the club's financial position far from safe. Indeed, it has taken the admirable efforts of the Hearts support to secure fiscal matters in the short-term.
Such matters are again due to come into sharp focus on Thursday, with the resumption in Edinburgh of a £1.75m tax tribunal between Hearts and Her Majesty's Revenue and Customs.
The hosts had opened brightly before Celtic took the lead. Kris Commons was the architect, with a cross from the left flank that was expertly converted at the back post by Lassad. To the Tunisian's credit, he had made a difficult finish appear perfectly easy.
Hearts should have offered an instant reply. Instead, Callum Paterson failed to connect from three yards out when seeking to meet a Ryan Stevenson free-kick. That wastefulness was seriously costly. As the Hearts defence failed to clear their lines, Mikael Lustig slammed the second goal into Jamie MacDonald's bottom right-hand corner.
Hearts again mounted a response, this time finding Celtic's goalkeeper Fraser Forster in outstanding form. Forster produced an excellent double to deny Stevenson's free-kick and a rebound header from Marius Zaliukas.
Stevenson's next intervention was even more unfortunate. The home midfielder deflected a Charlie Mulgrew cross past MacDonald and the contest was over.
Forster again produced acrobatics in the Celtic goal, five minutes after the restart, to turn a fierce, low Kevin McHattie free-kick just wide of the post.
In general though, and unsurprisingly given Celtic's earlier potency, the second period was a non-event. There was time for a late Celtic fourth as Gary Hooper volleyed a perfect Mulgrew cross past MacDonald, and for Hearts to waste a penalty chance as Forster denied Zaliukas.