The Saints players applauded the champions on to the park before kick-off but would not have wanted to extend that act of sportsmanship to giving the home side a goal of a start, which is exactly what Joe Ledley's quick-fire opener represented.
Gary Hooper looked like he handled Anthony Stokes' long ball as the Parkhead side broke but referee Alan Muir allowed play to continue, probably certain that Tom Scobbie would clear. However, the Perth defender mis-kicked inside his own box to Scott Brown and the visitors were in trouble.
Hooper regained possession, passed to James Forrest who set up Ledley at the edge of the box and the Wales midfielder rifled an unstoppable drive past the flailing Alan Mannus.
It seemed only a matter of time until Celtic doubled their lead and it came when Gregory Tade was penalised for a foul on the Parkhead captain, 35 yards from goal on the right-hand side.
A trademark delivery from Charlie Mulgrew zipped past several heads inside the packed six-yard box and past Mannus into the far corner.
Within seconds of the restart Saints midfielder Liam Craig volleyed a cross from Steven MacLean over the bar at the back post, indicating that the Taysiders were looking to make a better fist of the second period.
However, in the 51st minute, just after Victor Wanyama and Rowan Vine were booked for a spat, Celtic increased their lead further following another speedy break, when Gary Hooper set up Forrest to shoot low past Mannus.
Georgios Samaras missed a great chance when the St Johnstone defence hesitated in dealing with a deflected Emilio Izaguirre cross, the Greece international flicking his leg at the ball which flew wide from eight yards.
Not that it mattered much. The game was well over, the final result was the only thing up for grabs. And there was time for Frazer Wright to compound his side's miserable afternoon when he headed a Mulgrew corner into his own net.