Celtic lost for the first time in the Premier League in a year thanks to a surprise 2-0 defeat by St Mirren in Paisley.
Home captain Mark O’Hara headed Saints two minutes from the end of a first half in which a much-changed Hoops team was out of form.
Giving the visitors’ defense a difficult afternoon, Burly Buddies forward Jonah Ayunga headed in the 53rd minute of the second half and Ange Postecoglou’s men had no reply.
It was a momentous win for Stephen Robinson’s resilient and well-organized side – St Mirren’s first league win at home against Celtic since March 2010 – and ended the Hoops’ unbeaten league record, which stretched back to a 1-0 loss at Livingston on 19.09 .2021.
Celtic go into the international break two points clear of Old Firm rivals Rangers at the top of the league and perhaps that was a reminder that there is still work to be done to defend their title.
After Wednesday night’s 1-1 draw with Shakhtar Donetsk in the Champions League, Postecoglou heralded the move with former Saints player Aaron Mooy, Anthony Ralston, Stephen Welsh, David Turnbull, Daizen Maeda and Liel Abada, while Scott Tanser is on the Side came replaced Richard Tait for St Mirren.
Celtic supporters chanted ‘if you hate the royal family clap your hands’ and applauded for a minute in memory of the Queen before the game and a banner was held up repeating the same slogan.
The ball flew from end to end in the early stages and a Hoops attack saw a Turnbull header go wide after a Greg Taylor cross.
Celtic kept the upper hand at times but St Mirren were undeterred and sporadically pushed forward, taking the lead with a well-crafted goal just before half-time.
Midfielder Keanu Baccus played down the right flank against fellow Australian Ryan Strain and his deep cross was headed off by the unmarked O’Hara, who escaped Mooy’s attention.
It came as no surprise that Postecoglou made substitutions at the break, with Portuguese winger Jota and Japanese midfielder Reo Hatate replacing Mooy and Maeda.
There was an attempt by the Parkhead men to pick up the pace but they were stunned again as Saints doubled their lead.
The Celtic defense couldn’t handle a long throw-in from Declan Gallagher and attacker Curtis Main headed over goal while Ayunga nodded from close range.
Postecoglou looked to the bench again and attackers Giorgos Giakoumakis and Sead Haksabanovic came on for Turnbull and Abada.
On the hour mark, St Mirren goalkeeper Trevor Carson conceded a deflected shot from Hatate, but moments later O’Hara headed Strain’s cross from six yards wide.
As Celtic increased the pressure, Carson saved a Giakoumakis header and a Taylor shot from long-range.
Taylor was replaced by Matt O’Riley in the 74th minute as Postecoglou went bust, but the Saints stayed defensively diligent and attempted to hand the champions a rare league defeat.