Forrester, 20, has been desperately unlucky since signing for Stags in the last window, arriving with an injured ankle and, having finally shaken that off, now injuring his other ankle.
However, he briefly showed fans what he could do and Clough said: “Will has damaged ankle ligaments and we're looking at maybe the first or second week in January with him.
“His loan deal was only until January, but it was always our intention to renew it. So as long as his injury is okay we'll look to do that.
“It was unfortunate as he was due to be with us a few weeks before he was, but he had a setback with his ankle and this time it's his other ankle.
“It was so innocuous. There was no one near him. He just passed the ball and then felt something pop. We hope he won't be too long.”
Having cleared up most of the injuries that had seen them go 14 games without a win, Stags have now seen the injury list numbers creeping up again, despite a superb run of nine wins in 10 games.
“We were seven out on Saturday again, with quite a few of those being defenders,” said Clough.
“John-Joe O'Toole has had an illness and he may be available for Saturday, but if not then next week.
“We're hoping Danny Johnson won't be too far off – a couple of weeks and he might be available for the Christmas period.
“If he doesn't make Saturday then Ollie Clarke should also be available for the three games over Christmas. That will certainly help us.
“James Perch is out for the season, Kellan Gordon won't be available any time soon and Will Forrester into January.”
He added: “We had 10 outfield players train this morning after the Sunderland U23s game.
“Over the next two weeks it's all about getting the balance right between the training and rest.”
The next transfer window opens soon, but Clough said: “I don't think there will be too many changes in January. It will depend on the loan situations – who we keep and if any clubs ask for their players back.
“Otherwise it will depend on injuries short-term or long term as to what we do.
“The squad is coping pretty well at the moment. We need a little bit of cover in one or two positions, but there won't be wholesale changes.”
At least Stags look like getting Burnley loanee Richard Nartey back soon, making his return in an FA Premier league Cup U23 1-1 draw at Sunderland on Monday night.
“It was good to get people a game who needed one,” said Clough.
“Richard Nartey was the main one. He hadn't played for 10 and a half weeks. So to get him on the pitch and get him 90 minutes was very important.
“James Gale had 65 minutes but got a knock and Tyrese Sinclair got nearly 90 minutes in, Ryan Burke as well.
“So, apart from Harry Charsley, all those from the bench on Saturday played.
“Jason Law returned a positive lateral flow test just before they got on the bus yesterday so he missed out.
“But we had some good youngsters from the academy playing as well and it was a good experience for them against a pretty strong Sunderland team.
“Tyrese did get hurt near the end but he is walking round okay this morning. It was just an impact injury – a sort of knee on knee clash. But he should be okay.”