Liel Abada fired a severely depleted Celtic side to victory over St Johnstone as Kyogo Furuhashi suffered fresh injury trouble in Perth.
Abada struck either side of Furuhashi appearing to aggravate a hamstring problem and the Israeli was denied a hat-trick goal on several occasions.
Substitute Chris Kane headed the hosts back into contention but stand-in Celtic captain Nir Bitton sealed a 3-1 cinch Premiership win, which briefly closed the gap to leaders Rangers to three points before their rivals beat St Mirren.
Celtic had already been missing eight players before the likes of Scott Bain, Callum McGregor, Anthony Ralston, Greg Taylor and Liam Shaw dropped out. The Hoops then handed a debut to their 18-year-old former Scunthorpe striker Joey Dawson as a 15th-minute replacement for Furuhashi.
Liam Scales and James McCarthy were in the starting XI.
With new crowd limits of 500 coming into force in Scotland, the Saints season-ticket holders who were successful in the ballot witnessed an eighth consecutive defeat.
After his side failed to convert 31 shots in a goalless draw against Covid-hit St Mirren in midweek, Celtic manager Ange Postecoglou brought back Furuhashi after the Japan forward missed games either side of his match-winning Premier Sports Cup final double.
Celtic had Carl Starfelt back from suspension in a back three and had Vasilis Barkas in goal in a new-look starting line-up, which was however full of recognisable players. Their bench was light on experience and included 16-year-old Ben Doak, who was looking to become the club's youngest player of all time.
Saints had one fresh Covid absence. Murray Davidson was absent while Kane was only fit for a place on the bench after being the first of four other players to end self-isolation stints.
Celtic took nine minutes to settle the nerves of their fans who were watching or listening from home, and the dozen or so who tried to get a glimpse of the action from a hill and even up a tree outside McDiarmid Park.
Saints twice lost the ball in quick succession in their own half and Josip Juranovic delivered a perfect low cross for Abada. The Israeli winger's initial shot was brilliantly saved by Elliott Parish but the Celtic player got his head to the rebound amid a clutch of bodies and knocked it into the net.
Tom Rogic was off target with a couple of chances before threading the ball through for Abada to slot into the corner in the 22nd minute.
Juranovic had an effort saved before Parish made a better stop after Bitton had played Abada clean through.
Parish denied Liam Scales from close range and Abada had two more openings before the break but was ultimately crowded out by the Saints defence.
The half-time whistle was met by boos from the fans, whose only glimpse of hope had been a cross which led to a stretching Stevie May heading well over.
Little changed at the start of the second half. Parish again produced an excellent stop to thwart Abada following Rogic's through pass, and Liam Gordon diverted Scales' cross just over his own bar under pressure from Abada.
Saints improved and got back into the game in the 69th minute after Starfelt gave the ball away. Kane ran on to Viv Solomon-Otabor's cross and steered a header into the far top corner.
Jacob Butterfield shot wide from distance for the hosts but Celtic generally kept the ball after Kane's goal.
They killed the game off in the 82nd minute after a spell of possession down the left flank. Scales passed the ball inside for Bitton and the midfielder placed the ball inside the near post from 16 yards.
Dawson was denied a debut goal by Callum Booth's goal-line clearance.
Alfredo Morelos continued his fine form under new Rangers boss Giovanni van Bronckhorst with another goal in a routine 2-0 Premiership win for the leaders over St Mirren.
With attendances capped to 500 due to government restrictions, Ibrox echoed to cheers in the 13th minute when attacker Scott Wright headed the hosts into the lead and again in the 26th minute when the Colombia forward hammered in his sixth goal in eight games under the Dutchman.
Morelos had several other attempts to further increase his goal contribution in a one-sided match in which the visitors offered little in attack.
Van Bronckhorst is unbeaten in nine games since taking over from Steven Gerrard and his side go into the rescheduled winter break still six points ahead of Old Firm rivals Celtic.