James Forrest may have appeared a one-man weather vane with a remarkable 30-minute four-goal first-half haul that handed Brendan Rodgers the biggest win of his two-and-a-half year tenure.
The winger demonstrated ruthless running power and finishing to condemn Tommy Wright to the heaviest loss of his six years at the St Johnstone helm.
However, as Celtic claimed as many goals in 90 minutes yesterday as they had in their previous seven games, the visitors could count on a flurry of forward players to bury opponents who simply froze in the face of such an onslaught. Forrest was to the fore in every respect, transforming his fortunes just days after receiving a straight red card and conceding a penalty as Celtic lost 3-1 to Salzburg in the Europa League.
“After Thursday night it was disappointing for everyone, especially me personally,” Forrest said.
“We wanted another game quickly to get over it, so there is no better way to do that than scoring six goals and keeping a clean sheet.
“That’s the first time I have scored four goals for Celtic so it’s great. The manager has been wanting us to become more ruthless again and I think you saw that hunger from us from start to finish.
“We couldn’t have done much better - a result like that has been coming. We have been playing okay but not taking the chances, but we did that today and the score reflects it.
“Getting the goal early helps, after that we were pressing high up the park and creating chances. The goals were unbelievable, there is nothing better for your confidence than scoring.
“Sometimes you play well and don’t score, so that isn’t always remembered.”
Celtic looked more like their double-treble winning selves at McDiarmid than at any point in the previous two months, but Forrest was reluctant to draw parallels, instead opting to slap down talk of any dressing room discord.
“We have heard people say that but since the manager came in the changing room has been very solid. It’s easy to say there is a split in the changing room when you get a few bad results.
“But you can see we are getting there, there is definitely no split,” he insisted.
“You can’t keep talking about the last two seasons, they are in the past now. It is a new one, the league is tougher because teams have improved. “It’s getting harder every year and we have to make sure we keep putting in more performances like that. Slowly but surely we are getting there.”
Chances were exchanged between the two sides before Forrest set the ball rolling with a fine strike on the quarter hour mark. A slip by Scott Tanser allowed the winger to bore into the box, where he fed Tom Rogic, who then slipped it to Odsonne Edouard. The striker’s effort was saved by Zander Clark, but Forrest was on hand to steer the ball home despite the ‘keeper getting a hand to it.
Wright admitted afterwards his side could have lost ten but for the half-dozen stops made by Clark. He also accepted that Celtic’s biggest ever win away to St Johnstone owed everything to Forrest proving unplayable in the first period.
After Edouard had made it 2-0 with a big backlift that allowed him to plant a low effort in the far corner 22 minutes in, the Scotland winger took ownership of the encounter.
His hat-trick took just over 20 minutes to complete. A scintillating move started when Edouard found him as he accelerated through the middle of a non-existent backline was followed by him playing a one-two with Rogic before stroking the ball into the bottom corner from just inside the box for his second.
That made it 3-0 on the half-hour mark. By the 38th minute Forrest had his third, pouncing on a loose ball midway inside the St Johnstone half and striding forward before coolly slotting it under Clark.
Seconds before the interval he became the first Celtic player to score four goals in an away match since Maciej Zurawski when Rogic released him on the run and he tucked the ball in the far corner without breaking stride.
Fears over what further damage might be inflicted on a bedraggled Perth side intensified when Danny Swanson brutally wiped out Forrest to earn a straight red only three minutes into the second period.
The surprise was that it took Celtic until the 85th minute to add a sixth, Callum McGregor guiding in from a Mikael Lustig cut-back.
St Johnstone: Clark; Foster (Anderson 45), Shaughnessy, Kerr, Tanser; Wright, Wotherspoon (Craig 78), Callachan, Alston, Swanson, McMillan (Kane 64). Subs: Hurst, Nydam, Watt, Kennedy.
Celtic: Gordon; Lustig, Boyata, Benkovic (Simunovic 60), Tierney; Forrest, Rogic (Morgan 70), McGregor, Ntcham, Edouard; Griffiths (Sinclair 60). Subs: Christie, Izaguirre, Bain, Mulumbu.
Referee: Kevin Clancy.