Speaking to BBC's Sportsound programme after the game he said: "I'm delighted. It was an outstanding team performance with some outstanding individual performances as well.
"My only criticism would be of the way we approached the game initially. In the first 15 minutes there were a few bad habits creeping in that we want to eradicate. We were inviting pressure we didn't need to.
"Once we solved that we were outstanding, especially to score five after the quick turnaround from Wednesday night, with five different scorers. Second half, we were magnificent. That's 12 goals in two league games - I can't ask for any more than that."
Celtic went behind to an early Liam Donnelly goal and, despite finishing the half in front through goals from Kristoffer Ajer and Leigh Griffiths, struggled against Motherwell for much of the first 45. In the second half the visitors took control and scored a further three through James Forrest, Odsonne Edouard and a Ryan Christie penalty.