It looked for all the world to be a Boxing Day hangover manifesting as a football match.
A near empty McDiarmid Park, a threadbare Celtic shorn of yet more key players and a St Johnstone team managing to end the most successful year in their history under real threat of relegation.
But Ange Postecoglou is steadfastly refusing to reach for the excuses and his patchwork side followed their manager's lead with a resilient victory in Perth.
Liel Abada's double and and a rare goal from stand-in skipper Nir Bitton capped a comfortable win - especially given the depth of Celtic's injury list.
Callum McGregor, Greg Taylor, Joe Hart and Anthony Ralston added to the ensemble cast of absentees amid talk of a Covid outbreak at Parkhead.
But what was left in green and white - including the lesser seen Vasilis Barkas in goal - made relatively light work of the Premiership's bottom side, even despite Kyogo Furuhashi's bothersome hamstring holding up for just 15 minutes.
Sub Chris Kane reduced the arrears for Saints with 20 minutes to play but Bitton's well-taken collector's item snuffed out any hope of a comeback.
The upheaval on the teamsheet certainly wasn't evident in the opening stages as Celtic pushed for - and were soon rewarded with - a deserved opener.
James McCarthy pinched the ball in midfield before Josip Juranovic did likewise on the flank and his low cross was turned in at the second attempt by Abada, however cruel it was on Saints keeper Elliot Parish after a stunning initial save.
Joy was short lived, though, as a darting Kyogo run in behind was curtailed by the forward's hamstring failing him again.
To their credit, Celtic responded to yet another setback by continuing exactly as they had done from the first whistle.
Tom Rogic's delightful take was the trigger for Abada to run in behind and he swept home a second from his team-mate's perfectly weighted pass.
It was exactly the ruthless Celtic had lacked in Paisley, albeit they were being aided and abetted by a quite dire Saints performance.
There were hospital passes aplenty being carelessly strewn around by the men in blue and when Ali Crawford was next to give it away, it took another great stop from Parish to deny Abada his hat-trick as Celtic looked to pounce.
Debutant Joey Dawson, on for Kyogo, was next to have a go with a snapshot that he never quite caught as he'd have liked.
But even with the notoriously precarious 2-0 scoreline, it never felt as though Celtic would live to regret any missed chances.
Rogic was being afforded the freedom of Perth to pull the strings and he again played Abada through moments into the second-half, only for Parish to save from the Israeli again.
In desperate need of a spark, Callum Davidson introduced Kane and Glenn Middleton off the bench, and it was the former who breathed fresh life into the game.
A dreadful pass from Carl Starfelt proved costly as Liam Craig found Viv Solomon-Otabor and his pinpoint cross was superbly headed beyond Barkas.
Suddenly, Saints fancied it again and Jacob Butterfield's drilled effort from distance pulled just wide of the post.
It was an all-too brief revival, however, as Bitton strode forward into the box and and struck beyond Parish to seal the points.
Get the latest sports headlines straight to your inbox by signing up for free email alerts
