Captain Callum McGregor rescued Celtic with a late leveller as the Hoops twice came from behind to draw 2-2 with St Mirren in a pulsating encounter at Parkhead.
Buddies boss Stephen Robinson had promised to have a go at the cinch Premiership champions and striker Curtis Main gave the visitors a shock lead after four minutes.
Hoops attacker Kyogo Furuhashi levelled with a powerful drive in the 15th minute only for Main to restore the visitors’ lead five minutes from the interval.
Main should have added to his tally on three occasions after the break and the Buddies were made to pay when McGregor equalised with nine minutes remaining to avoid a successive league defeat after losing 3-0 to Old Firm rivals Rangers last week.
St Mirren beat Celtic 2-0 last September but had suffered three heavy defeats by the Hoops subsequently, although they were well worth their point on this occasion.
It was Celtic’s first home game since they clinched the title against Hearts at Tynecastle two weeks ago and Greg Taylor, Furuhashi and Daizen Maeda came back in, along with Tomoki Iwata who was playing in a more unfamiliar centre-back role in place of Yuki Kobayashi.
Midfielder Keanu Baccus and defender Thierry Small started for the visitors, who got off to a stunning start.
Following a long clearance from Buddies goalkeeper Trevor Carson, a mix-up between Iwata and right-back Anthony Ralston allowed the ball to drop to Main inside the box and he turned inside the latter before shooting low past keeper Joe Hart.
However, the lead evaporated when midfielder Reo Hatate took a pass from Iwata and slipped in Furuhashi to slam the ball high past Carson from 12 yards for his 31st goal of the season.
Hatate soon thundered a shot just over the bar and midfielder Matt O’Riley’s drive deflected off Baccus and almost sneaked in at the near post before Carson turned it behind for a corner which came to nothing.
Saints passed up a great chance when Hart parried Greg Kiltie’s cross straight to Ryan Strain and he knocked it past a post from just a few yards out.
However, there was even more drama moments later when Main headed into the net from eight yards out after latching on to a Mark O’Hara header as Celtic struggled to clear their lines.
After a long VAR check for offside, referee David Munro confirmed the goal put an unusual sheen on Ange Postecoglou’s half-time team talk.
Three minutes after the restart Strain stood a cross up to the back post and Main leapt highest only to head past a post.
Celtic were rattled again but came back and, in the 54th minute, from Jota’s cross, Maeda lifted the ball over the bar from six yards before Main, again, headed a Strain cross wide at the other end.
Maeda prodded the ball wide from close range before O’Reilly, Hatate and Maeda were replaced by Sead Haksabanovic, Liel Abada and Oh Hyeon-gyu as Postecoglou re-energised his side.
The Paisley side were having to hold on, desperately at times but in a breakaway, Main beat Hart with a drive only to see the ball rebound off a post, with Oh striking the goalframe at the other end seconds later.
With time running out for the home side it was McGregor who came to the rescue when he curled the ball past Carson from the edge of the box to cheers of relief, and the Buddies had to withstand late pressure to emerge with a point.