The 28-year-old Argentine striker has not played for the Owls since August, following knee surgery.
In a season when the Owls squad has been decimated by injuries - with over a dozen suffering long-term injuries - the absence of talisman Forestieri has arguably been the biggest loss.
His pace and goals - 27 in 61 Championship starts - were big factors in Wednesday reaching back-to-back play-offs in the last two seasons.
But he returns to an Owls squad fighting to stave off relegation.
Forestieri is unlikely to be plunged into an instant return - Wednesday travel to Leeds United tomorrow - but could return to first-team duties after the two-week international break.
The Owls’ injury crisis is starting to ease, with midield duo Barry Bannan and Sam Hutchinson, plus Dutch defender Joost van Aken all in contention to play at Elland Road.
“Fernando Forestieri is making very good progression, and tomorrow (Friday) he can train for the first time with the team after six months (out),” said Owls manager Jos Luhukay.
“If everything goes very positive in the next two weeks, maybe Marco (Matias) and Fernando are very close to the team. That’s the happy news.”
The sad news came in the form of 21-year-old midfielder Sean Clare, who will miss the rest of the season with an ankle injury.
Clare was drafted into Wednesday’s first-team, after being recalled from a loan spell at Gillingham, and has impressed in his five appearances in 2018.
Clare - out of contract in the summer - will see a specialist next week to assess if he needs surgery.
“Sean is very disappointed and so are we,” said Luhukay. “He’s not available for two months. One player comes back in and one goes directly out so it is not an ideal situation.
“The contract has been ready for a couple of weeks for Sean.
“It is also a difficult situation for him. He could be out of football for three, four or five months and his contract is finished in the summer.
“He can sign with us and we have given him the future and what we would like to do with him.”
Owls trio Hutchinson, Bannan and van Aken have yet to play under Luhukay - who replaced Carlos Carvalhal in January - but could feature at Elland Road.
All three have not played since December, with Hutchinson managing just seven appearances all season.
“Joost van Aken, Sam Hutchinson and Barry Bannan are training 100 per cent with the team,” confirmed Luhukay.
“Sam and Joost have played with the Under-23s, they are in a very good shape.
“They have done a lot of work in the last week, so they are options for Saturday.
“They are 100 per cent and I am very happy to have options in my squad. I have three options for my squad, and maybe my first XI.
“Barry has been out a long time but we know he’s a very good player.
“If it goes good for Barry today and on Friday, I think we will put him in the squad for Saturday.”
With midfielder Kieran Lee and goalkeeper Keiren Westwood also edging closer to full fitness, Wednesday’s first-team squad is looking a lot healthier as they approach the final nine games of the season.
The Owls are eight points clear of the bottom three, but know they probably need at least two more wins to guarantee their Championship status.
With five of their remaining nine games away from home - and Luhukay yet to taste victory outside of Hillsborough - Wednesday are not clear of danger just yet.
“We have spoke with each other, we know what we have done, what we must do, and what we can do better,” said Luhukay, whose side are on a seven-game winless run.
“There’s no problem with motivation.
“The position in the league does not lie. We must work 100 per cent in every game to get in a better position.”
Luhukay’s has an unbeaten record in Yorkshire derbies since arriving in Sheffield.
He has engineered draws at Bramall Lane, the Riverside and Oakwell, but the Dutchman has been impressed by Leeds this season.
Mid-table United are 12 points better off than Wednesday this season, but with the play-offs out of range, Paul Heckingbottom already has one eye on next season.
“I think they are a very strong team,” admitted Luhukay. “They have unbelievable offensive quality. All four strikers are very effective. We have a lot of work on Saturday to stop their quality.
“Leeds, in the last weeks, have also not had good results, so they also will look for success. It will be an interesting game.”
Wednesday put in one of their best displays of the season when the Yorkshire rivals met at Hillsborough in October.
Two goals from Gary Hooper and a late Lee goal ensured a 3-0 win for the Owls - one of just five Championship victories at Hillsborough all season,
Luhukay said: “I think in a derby you must have the passion and a winning mentality to get a good result. Both sets of fans will give 100 per cent support, so we must give everything we have.”