Second-half goals from Cameron Carter-Vickers and Callum McGregor earned Celtic another crucial three cinch Premiership points against St Mirren.
Carter-Vickers lashed home from close range to ease the tension at Parkhead 10 minutes after the break after Celtic had struggled to cut through a well-drilled visiting team.
The opener did not open the floodgates by any means but Celtic’s lead was never threatened before McGregor doubled it in the 81st minute when he drilled home from inside the box.
The 2-0 victory kept the leaders three points clear of Rangers with nine games remaining.
Manager Ange Postecoglou had warned the leaders would face a battle in every game of the run-in with every team in the league playing for something, and St Mirren provided just that.
Ahead of the game, only Celtic had collected more Premiership points than St Mirren in 2022, despite the Buddies playing one less game than most of the division.
Celtic were again without Giorgos Giakoumakis, who was absent for the goalless draw with Hibernian on Sunday through illness, and they missed his penalty-box presence at times.
St Mirren manager Stephen Robinson lined up with five defenders with the added protection of Alan Power and Alex Gogic in central midfield. Greg Kiltie and Jordan Jones were tasked with supporting lone striker Curtis Main when they were not tied up with defensive duties themselves.
St Mirren had an early let-off when Charles Dunne sliced a clearance off his own bar following a cross from Jota.
The Portuguese winger soon provided two decent chances from the left. Liel Abada’s side-footed effort was parried by Jak Alnwick and Josip Juranovic was too high with a fierce first-time effort from just outside the box.
Richard Tait’s low cross caused some danger at the other end but Joe Hart ultimately dealt with it.
Celtic’s best first-half chance came from a set-piece. Daizen Maeda peeled off the goalkeeper to meet Matt O’Riley’s inswinging free-kick but headed well wide.
There were clear signs of restlessness in the home support and clear-cut chances proved elusive in the final stages of the half.
Both Maeda and Jota headed off target with their backs to goal and Alnwick made a meal of parrying the latter’s curling effort.
The frustration was even more audible just after the break when Celtic lost possession from a short corner and McGregor was forced into taking a booking to stop Jones breaking.
A more direct set-piece soon led to the opener. Jota delivered from the right after being fouled by Scott Tanser and Carl Starfelt got the first contact before Carter-Vickers volleyed home from inside the six-yard box.
Postecoglou brought on the likes of Tom Rogic and James Forrest and Celtic continued to play the majority of the game in St Mirren’s half without boasting their maximum fluency.
The cushion came after a good break down the right from Juranovic, whose cross ultimately fell for McGregor to fire into the far corner from 14 yards.
Postecoglou brought on Karamoko Dembele for the attacker’s first appearance since fracturing an ankle in pre-season.
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