But even though his side ruled the roost in almost every phase in Llanelli, Leinster boss Cheika is taking nothing for granted for next Saturday's return leg in Dublin.
"Next weekend is a massive game for us. We will never rub out the London Irish defeat until we have beaten them and losing at home to them at the start of the campaign was a real killer for us," admitted Cheika.
"We pride ourselves on the way we play at home and we want to redeem ourselves in front of our own supporters when we face the Scarlets in our second home Heineken Cup game.
"We may have taken five points at Parc y Scarlets, but that game is over and done with. Now we know we will be facing a fresh challenge at the weekend.
"The Scarlets will want to prove a point when they come to us and I expect more attacking football from them. They will be right up for it and they will be going for everything.
"We were highly motivated coming into the first game and they are going to be exactly the same at the RDS.
"We know we have got to fight for everything in this tournament and at least after this win we are still very much in the hunt."
Meanwhile, following returns from Scarlets, there are now additional tickets available for next Saturday's Round 4 clash at the RDS (K.O. 3.45pm).
Tickets are available in the Leinster Rugby Store and Spar shop in Donnybrook, Ticketmaster outlets nationwide and online here.