The Hoops went head-to-head with the Dons at Hampden Park to defend their Scottish cup glory.
Forrest scored an absolute peach of a goal, right before the end of the first-half, to give the Celts the lead.
The winger emulated Argentine star Lionel Messi to score a blinder from outside the box.
The Dons’ goalkeeper was lost for words when the ball found the nets.
Later, goals from Odsouune Edouard and Tom Rogic were enough to wrap-up the game against Derek McInnes’ side.
Forrest has been phenomenal this season and pivotal for his side in the title race.
Last night’s goal marked his 13th of the season, having already bagged nine assists to his name as well, making him a serious contender for the player of the year award.
The 27-year-old also scored the decider in the Old Firm derby last month in the final third of the game.
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Neil Lennon, the makeshift manager, has won six games out of 8, without facing a single defeat.
And the chances are high for the Bhoys to win a domestic treble this season.