Luis Palma’s late strike saw Celtic secure a win on an emotional Premiership trophy day for retiring goalkeeper Joe Hart.
After wrapping up the league in style at Kilmarnock in midweek, the Hoops were looking for more of the same in their final league game of the season.
But St Mirren, back in Europe for the first time in 37-years, had other ideas as Mark O’Hara slammed home the opener inside the opening 10 minutes.
Matt O’Riley levelled the game, before O’Hara fired in his second from the penalty spot after Stephen Welsh clattered into Toyosi Olysanya, with Kyogo Furuhashi pulling the Hoops level again before the break.
There was an emotional tribute to Hart in his final Celtic Park appearance as he left the pitch with minutes left to play before Palma really got the party started when he secured the champions victory.
Christmas comes early for Celtic
Santa brought the Premiership trophy out at Parkhead to applause as the Hoops fans made up for booing him in December, when they feared the Premiership title was heading to Rangers.
He was among those soaking up the sunshine as the players emerged to a guard of honour from St Mirren.
And Welsh should have given them the perfect start when he met Palma’s corner but instead headed wide.
Please use Chrome browser for a more accessible video player
St Mirren’s Mark O’Hara fires the Saints into a shock lead against Celtic.
Instead, St Mirren showed their intent to spoil the party when O’Hara found the bottom corner to fire the visitors ahead after just seven minutes.
The Buddies continued to cause problems but, after striking the bar, O’Riley took advantage of a loose ball and slammed home the equaliser in the 21st minute.
Please use Chrome browser for a more accessible video player
Matt O’Riley draws Celtic level against St Mirren.
They were trailing again minutes later as O’Hara converted from the penalty spot after Welsh’s error, and Keanu Baccus’ shot was blocked before O’Hara hit the post as Stephen Robinson’s side really looked to dampen the celebrations.
Celtic were screaming for a penalty after Kyogo was brought down by Alex Gogic, but a VAR check showed he was offside.
Please use Chrome browser for a more accessible video player
Mark O’Hara’s penalty restores St Mirren’s lead over Celtic
The Japan striker did pull the champions level before the break, turning home Reo Hatate’s cross, with Palma sending a diving header just wide soon after.
Hart, retiring at the end of the season, was close to tears as he emerged for the second half to see a tribute unfurled in his final game at Celtic Park as “Joe, Joe super Joe” rang around the stadium.
Please use Chrome browser for a more accessible video player
Celtic fans showed their appreciation for their goalkeeper Joe Hart who was making his final appearance at Celtic Park against St Mirren.
Celtic started the second half strongly with Nicolas Kuhn’s effort blocked and a Kyogo strike saved by Zach Hemming.
St Mirren weren’t letting them have it their own way though and Olysanya came close twice in quick succession, knocking one wide and Nawrocki clearing the other.
Please use Chrome browser for a more accessible video player
A late Luis Palma goal means Celtic finish the season with a win as they see off a spirited St Mirren.
Callum McGregor handed Hart the captain’s armband as he was replaced before the goalkeeper was given an emotional farewell as he was substituted after Palma wrapped up the win, converting Anthony Ralston’s cross at the back post.
How to book Fury v Usyk on Sky Sports Box Office
It’s one of the biggest sporting events in a generation. Tyson Fury and Oleksandr Usyk collide for the undisputed world heavyweight championship on Saturday May 18, live on Sky Sports Box Office.