James Forrest provided Celtic supporters with the ending they desired by scoring a goal in extra time against St Mirren, extending his streak of scoring for the club to 16 consecutive seasons.
Forrest waited until the 38th game of the league season to score, on a day when he was selected to present the William Hill Premiership trophy to his team-mates before Callum McGregor lifted it for the fourth consecutive year.
St Mirren were in the lead thanks to Jonah Ayunga's goal – and at one point were on track for Europe – until Alistair Johnston assisted teammate Forrest, who placed the ball inside the near post to level the score to 1-1.
Forrest injected much-needed urgency and creativity into the Celtic team upon entering the match in the 55th minute, with home fans honoring him with banners and songs in his name.
The winger then went on to secure his 26th winners' medal of his Celtic career, surpassing the previous record held by Bobby Lennox.
St Mirren fans were proud of their team's performance and their unbeaten record in the post-split fixtures, but were disappointed after narrowly missing out on fifth place.
Aberdeen's defeat against Dundee United, courtesy of Sam Dalby's goal in the 63rd minute, dashed their hopes of European qualification even before Forrest's equalizer.
In the first half, St Mirren adopted a defensive approach, protecting their box and goalkeeper Zach Hemming, who handled several corner kicks.
St Mirren striker Mikael Mandron came close to breaking the deadlock in the first half, testing Kasper Schmeichel with a shot from a tight angle.
Nicolas Kuhn had a potential penalty claim early in the second half when he resisted Richard Taylor's challenge instead of going down. However, the winger set up Paulo Bernardo, who delayed his shot and missed the opportunity.
St Mirren surprised Celtic Park in the 51st minute when Liam Scales cleared Declan John's long free-kick, but only as far as Ayunga, who slotted a left-footed shot low into the corner from 16 yards.
Celtic needed a sense of urgency, which they got with the introduction of Forrest, who entered the pitch along with Luke McCowan and Yang Hyun-jun.
Forrest was influential as McCowan and Callum McGregor had attempts blocked before he provided an opportunity for Daizen Maeda with impressive wing play.
Maeda, with 33 goals this season, missed a chance from close range, heading over from a yard out.
St Mirren had opportunities on the counterattack, with Mandron heading wide and Schmeichel denying Roland Idowu.
Celtic increased the pressure in the final moments. Substitute Johnny Kenny displayed speed to get past the visiting defense, but Hemming made a double save before stopping Yang's acrobatic effort moments later.
Despite calls to 'shoot', Forrest opted to set up Jeffrey Schlupp, only for Marcus Fraser to make a crucial block.
The 33-year-old saw previous attempts thwarted before his memorable finish.