But the winger is confident that, if he fails to regain full fitness in time, Neil Lennon has enough quality in his squad to cope with the punishing run.
Forrest has been out of action with a hamstring injury since the 2-0 defeat to Kilmarnock at Parkhead in the SPL at the end of October.
However, he is making steady progress and has returned to full training at Lennoxtown this week.
"I am doing all right, working hard to get over my injury, and I'm hoping to be back in action very soon," confirmed the Scotland international.
Having the 21-year-old available again would give Celtic manager Lennon, whose side has eight games in December, a huge lift.
But if Forrest has to wait until after the two-week winter break in January to make his comeback he has complete faith in his team-mates.
The Hoops have struggled this season – after big European matches especially – when they have been forced to field fringe players and kids.
The Glasgow giants have lost to Kilmarnock and Inverness Caley Thistle and drawn with Hibs and St Johnstone at home.
Not surprisingly, the 1-1 draw with part-time Irn-Bru Second Division side Arbroath in the William Hill Scottish Cup was not well received by an incredulous support.
Many fans feel, with experienced internationals like Miku, Beram Kayal, Lassad Nouioui and Thomas Rogne in the side, performances and results should not suffer.
But Forrest believes the criticism of the team has, at times, been excessive and is confident everyone in the Celtic squad is more than capable.
"It is a squad game and if I can't play then we will have others who can come into the team and do a good job," he insisted.
"I watched the game with Arbroath last month and thought the young lads who came in that day, Joe Chalmers, Rabiu Ibrahim and Dylan McGeouch, all did very well.
"Okay, at the end of the 90 minutes the team didn't win and perhaps that looks bad to some people. But the overall performance was decent.
"Yes, we should be looking to win every game that we play at home, be it in the league or cup or in Europe, and can have no excuses if we fail to do so.
"But the stats after the Arbroath game showed that we had 19 shots on target. It was really just one of those games where we couldn't get the ball in the back of the net, try as we might.
"The young lads who were involved all train with the first team and any time a place becomes available they are all looking for a start.
"We have got a lot of guys in the squad, but that can only help us at this time when we have two games every other week."
With fixtures against Ross County at home and Dundee and Hibs away coming up, Celtic will need to utilise their squad to the full.
That will mean Miku, the Venezuelan striker, and Lassad, the Tunisian forward, will be asked to chip in with goals.
With Gary Hooper, Georgios Samaras and Tony Watt all impressing this term, both men have struggled to force their way into the first team since arriving in the country. Miku and Lassad have just one and two goals to their names respectively.
Yet, Forrest has been impressed with their obvious prowess in the final third in the last few months in training as well as in matches, and has urged them not to get too downhearted at their lack of return.
He said: "Both players are doing all the right things whenever they play and getting themselves in good positions to score.
"In the Arbroath game their keeper pulled off a couple of absolutely amazing saves. Miku also hit the crossbar. Sometimes it's just not your day.
"They definitely shouldn't let it get to them. It is obvious they are very good players and will be able to do a good job for the team when they are called on."
He went on: "With the number of games we have in the cup, the league and in Europe everyone is going to be called on to play at some point and they will get their chance."
Forrest confessed that being out of action for so long had been hard to bear – especially with Celtic playing a host of massive Champions League matches against Barcelona, Benfica and Spartak Moscow in Group G.
But he has been delighted with how the Hoops have performed in Europe's premier club competition in his absence and is optimistic he can return and make his presence felt during the second half of the campaign.
He said: "It has not been the best being injured. It has been hard looking on from the sidelines. But that is what happens in football.
"You just have to take it on the chin and get on with things as best you can. That is what I have been doing. Hopefully I will be back in the team soon."