There was the intelligence to see how the game was developing in the early minutes, anticipating slack play from the Jags, pressing to help Celtic win the ball back in the build-up to his opening goal.
Moments later he had the technique to turn and strength to hold off Callum Booth before accelerating past Adam Barton. Then he showcased his quick feet and an emphatic finish. It was the second of an impressive hat-trick which has taken him to 16 goals for the season - six more than his previous best return.
Six days later the 26-year-old put in another excellent performance as Celtic defeated Zenit St Petersburg in the Europa League.
There is an argument to be made that Forrest has been both Celtic’s best and key player behind Scott Brown this season. Due to the quality throughout the team it was an unlikely scenario at the start of the campaign. Going back a further 12 months and that idea would have been unthinkable.
As Ronny Deila’s reign ended, Forrest had two feet out the door. All that was left was for the door to shut behind him having rejected a four-year deal. There would have been few tears shed among the Celtic support.
His presence in the squad was largely treated with apathy or disdain. To many he was a player who hadn’t lived up to his early promise, despite being only 24. Others were frustrated by his inconsistency and inability to regularly put his stamp on the game.
Arsene Wenger once said that a “good footballer is somebody who can offer the perfect solution in an unpredictable situation”. Forrest was somebody who rarely offered any solution no matter the situation.
The blind alley was a favoured destination if he hadn’t already turned back on a promising attack. When Forrest did cross it was often the same cross with the same result. There was a clear diffidence to his play, familiarity had bred contempt.
In the second half of the 2015/2016 season he played only 158 minutes in the league, his last outing coming at the start of March.
It was set to be an undignified exit for the youth product. But then came Brendan Rodgers; five words which have a great significance to a lot of people around Celtic Park.
“He’s obviously been on loan for a couple of years,” said Rodgers as he joked about Forrest’s form prior to his arrival, “but I want him back to play.”
That was the message Brendan Rodgers had for Forrest on arriving. The Northern Irishman saw a winger who he could work with and mold into an effective and dependable performer.
Rodgers needs to be able to trust his wide men, considering the responsibility they are given and work ethic required of them. Forrest has gained that trust, and perhaps more pertinently the trust of the Celtic crowd.
Any time the player has had a positive spell for Celtic the expectation was that it was ephemeral, but he is now in a position where he is delivering on a game by game basis, winning over the implacable element of Celtic fans.
Not only is he a match winner but he is now becoming a rare breed of reliable wide man who, more often than not, delivers, at the very least, seven out of 10 performances. While he doesn’t have the x-factor of Patrick Roberts, it should be understood that he is better for the collective.
But what exactly has changed across the past two seasons?
When you compare this season’s stats with last season, Forrest is recording fewer shots, fewer crosses and fewer dribbles. So he must be a lot more efficient? Not quite. His crossing accuracy has dropped - from 36 per cent to 24.07 per cent - as has the percentage of shots he gets on target - 44.68 to 40.48.
As for assists, last season he recorded 0.4 per 90 minutes. This season it is down to 0.1 per 90 minutes.
How has he improved then? Why is he better? Can it really be said that he is an important player for Celtic?
Of course, because the numbers don’t tell the whole story.
Forrest is now a winger-wing-back hybrid. While many still talk about Celtic as a back four it is not so easily defined, with a more lop-sided formation bordering on three at the back. Forrest gives the team balance on the right.
It is easy to see why pundits and observers are easily confused. Forrest takes up aggressive positions when attacking. Such is Celtic’s control he can afford to do so in domestic competition, yet he doesn’t negate his defensive responsibility.
Under previous managers he was tasked with providing width, verticality and penetration, plus supporting his full-back. Under Rodgers he has to provide the former, while also carrying out the role of a de facto full-back.
That’s been seen on the European stage where he has provided big moments, including the crucial goal in the qualifier against Rosenborg. Then there was the “sensational” display at home to Bayern Munich, notching an assist. He may just be the answer to Scotland’s problem on the right, providing Alex McLeish plays with a back three.
To perform such a role is more than simply doing doggies for 90 minutes, running in straight lines. There has to be a tactical appreciation: which positions to take up, when to move infield, when to hold. Without the ball it is almost natural to him. With the ball, there has been a huge improvement.
Rodgers told the BBC: “He’s one of the best receivers of the ball I’ve ever worked with, whether it’s in a tight space or in the middle of the pitch. He’s getting real confidence in his game.”
High praise indeed from the Celtic manager, and perhaps a bit of hyperbole considering the players he has worked with. But the key word is confidence. In the last 21 months Forrest has increasingly played with a self-belief. He has the physical, technical and tactical qualities. The mental factor which seemed to be a hindrance has been removed.
Despite 12 winners’ medals and goals in three League Cup successes, plus nearly 300 club appearances, it is only of late that he is an undisputed key Celtic player, having evolved from boy to man.