Forrest was brought on as a substitute after an hour to make his first appearance since Boxing Day and showed great technique and composure to score Celtic's second goal. Kris Commons had opened the scoring from the penalty spot after being tripped by Simon Mensing, while Charlie Mulgrew put an extra sheen on the result.
Forrest will now join up with the Scotland squad ahead of Wednesday night's friendly against Estonia and Lennon was delighted to see the winger back to full fitness with the Champions League last-16 tie against Juventus now just a week away. "We've been desperate to get him in but the physios have been holding him back," said the Celtic manager.
"He got a few minutes today and we hope he will get some game-time with Scotland. We then hope he will play at Inverness next week and we can get him ready for Juventus."
The Celtic manager also expressed his satisfaction at a job well done. "We started strongly and it was a good professional display. I thought once we got the first goal the game would open up a bit more. Thankfully it did."
There was a worry, though, about so many of his players now leaving for international duty with the Juventus tie just around the corner. "We have got the biggest game in four or five years at the club coming, and we have players all over the world," added Lennon "I will make changes for Inverness next weekend. I'll keep the big boys thriving for the Juventus game."
Mensing felt that the penalty award given against him was unfair. "I thought the ref got that one wrong – he went down too easily and I know that for a fact," said the Raith defender. "Commons was doing it during the game and you can see he's a clever player."
The Celtic player, though, unsurprisingly disagreed. 'You can't trip players in the box," he said. "If he got a bit of the ball fair enough, but he didn't. I don't know what he expects me to do."
Grant Murray, the Raith manager, had no grumbles about the end result, though. "Even at 1-0 down we were still having a go at them, but their quality shone through."
william hill scottish cup Forrest goal eases progression into draw that tees up Dundee derby