Boss Neil Lennon was left perplexed after a firecracker incident followed Celtic's clinching goal in the 2-0 Ladbrokes Premiership win over St Mirren at the Simple Digital Arena.
Striker Timothy Weah headed in the opener after 14 minutes before Buddies keeper Vaclav Hladky saved an Olivier Ntcham penalty.
After substitute Ryan Christie sealed the win with a deflected shot five minutes from time, keeping Celtic 13 points clear of Rangers with just six fixtures remaining, the loud bang from a firecracker thrown on from one of the stands unsettled Hladky.
The Buddies keeper required some attention and his manager Oran Kearney admitted he had been tempted to take his players off the field.
Lennon, who revealed defender Dedryck Boyata is out for the rest of the league season with a ruptured hamstring, said it had been a "good night" for his side but was puzzled by what had had startled Hladky.
He said: "It serves no purpose in a football ground.
"I don't see the motivation for anyone to bring a flashbang or pyrotechnic into a stadium.
"The health and safety of the players and officials is paramount. It didn't just spook the St Mirren keeper but some of our players too.
"Ryan was also spooked and the goalie might have burst an ear drum.
"It delays the game when we have scored a goal and want to get going again. It serves no purpose whatsoever.
"The club have made a real stand in condemning it at times. I don't understand why people want to do that. There is no logic in it.
"Why does an individual want to bring that to a game? It doesn't impress anyone, it doesn't add anything.
"It just damages people – and it could have damaged a player.
"It damages the reputation of the good fans we have and we just don't want it.
"It's just totally uncalled-for at a time when we should be enjoying football and hopefully having a big (title) celebration in a week or two."
Kearney, whose St Mirren side remain two points clear of bottom side Dundee, had already used his three substitutes.
He said: "It is crazy to think we might have had to use an outfield player in goal.
"It is mad to think of how that possibly could have ended up.
"You are tempted to walk your team off the pitch.
"We have been beat tonight – the easiest thing for me to do is make a massive meal out of that and deflect away, but it is a huge deal.
"I had a brief chat with (Hladky) but had to rush out to do media stuff.
"We are hopeful that thankfully it hasn't ended up more sinister than it could have.
"I am standing 50 or 60 yards away and it made me jump. So if he is a yard (away) or however close, I dread to think the sound that came off."
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