Celtic turned on the style in their final league game but the title party was tinged with concern for the fitness of Kyogo Furuhashi and Alistair Johnston after the pair went off injured in a 5-0 win over Aberdeen.
Furuhashi went off after scoring twice in five first-half minutes to consolidate his place at the top of the cinch Premiership goalscoring charts.
The Japan international came off worse in a 50-50 with Aberdeen goalkeeper Kelle Roos and limped off five minutes into the second half despite initially trying to play on.
Johnston was making his comeback from the heavy leg knock he suffered during Celtic’s Scottish Cup semi-final win over Rangers and he went down holding his leg before making way in the 64th minute.
After collecting one point from the three games since clinching the title, Ange Postecoglou had picked 11 players that have a good chance of starting next Saturday’s final against Inverness, barring injury and the possible return of the suspended Daizen Maeda.
Celtic returned to winning ways in emphatic fashion as Carl Starfelt notched his first goal at Parkhead and substitute Oh Hyeon-gyu grabbed a double before the team collected the Premiership trophy.
The champions emerged to a guard of honour from Aberdeen, who clinched third place and a European spot in midweek and will be guaranteed group-stage football if Celtic win the cup.
Postecoglou, who was named Scottish Football Writers’ manager of the year earlier in the day, will join Jock Stein, Martin O’Neill, Brendan Rodgers and Neil Lennon in becoming a treble-winning Celtic manager if that happens and a full-stadium fan display referenced the club’s history before the game.
Huge images of Stein and Willie Maley filled both ends of Celtic Park with a banner declaring ‘stand on the shoulders of giants’.
Liel Abada made a lively start, before making way for James Forrest at half-time, and Celtic looked to have rediscovered the intensity missing since they won the title at Tynecastle.
Furuhashi missed two chances and Starfelt saw a header well saved by Roos before Greg Taylor’s pass set the forward up to finish into the top corner in the 27th minute.
The PFA Scotland player of the year soon scored his 27th Premiership goal of the season – three ahead of Hearts skipper Lawrence Shankland and Motherwell striker Kevin van Veen, who still has one game left.
Roos spilled Callum McGregor’s curling effort and Furuhashi reacted quickest to knock the rebound home.
Furuhashi was not far over from a tight angle before his chances of a hat-trick were ended by injury.
Celtic continued to dominate. Matt O’Riley hit the post, Jota was just wide with an acrobatic flick and Reo Hatate came close before Starfelt headed home O’Riley’s corner in the 78th minute.
Oh headed home four minutes later from Jota’s cross before doubling his tally in the last minute after the Portuguese winger had struck the bar with a free-kick.