The 29-year-old is yet to feature in December because of a knee injury.
“It's been a little bit more niggly than we thought.” said manager Garry Monk. “He's rehabbing well. It's dictated by the pain threshold.
“This weekend is probably not likely but we'll take it day by day.
“We hope he'll feature over Christmas but we'll take it step by step.”
Forestieri's absence has been more than mitigated by the triumphant return of Jordan Rhodes. The centre-forward marked only his second start of the season with a hat-trick at Nottingham Forest last week.
Until then it had looked a near-certainty that the Owls would try to move Rhodes's big wages off their payroll but if he can continue his goalscoring form, it will give them food for thought.
“We've been delighted for Jordan, he's worked very hard behind the scenes,” said his manager. “He's had a really positive week. If we can get him to contribute to the level he has, he's a great asset. It doesn't alter anything going into January but at this moment all I want to think about is the games coming.”
Midfielder Sam Hutchinson serves the final match of a two-game suspension, but that apart, Monk has a full squad to choose from.
Kieran lee missed the 4-0 win at the City Ground to attend the birth of his child, but has been back in training all week.
The game kicks off at noon on Sunday for the benefit of television. The Robins go into the game a point behind Wednesday, who are in fifth.