The Owls centre-half missed Tuesday night’s surprise 3-1 defeat at Burton Albion through injury, but returned to training today.
Wednesday were forced to play two midfielders as emergency centre-halves in Sam Hutchinson and Jose Semedo - the latter limped off in the first half to compound the Owls injury problems - but Lees will partner Hutchinson on Saturday lunchtime.
On Lees, Owls head coach Carlos Carvalhal said: “The panorama before the last game was not so good but in this moment it is much better.
“Tom Lees is training normal and has completely recovered. He trained today and is 100 per cent. He is a very, very important player to us.
“He is a fantastic player. He’s one of the best central defenders in England not just in the Championship to me.”
Portuguese midfielder Semedo had a scan today on his hamstring, the club keeping their fingers crossed the injury isn’t serious.
“We don’t know yet,” Carvlahal replied when asked about Semedo. “He’s had an exam today. We don’t yet have the results. I think he will be out of the game.”
But there was better defensive news for the Owls, with captain Glenn Loovens back in training after he missed the start of the season through surgery in the summer.
He is unlikely to feature this weekend, though.
Carvalhal said: ”Glenn Loovens in a very, very short time will be involved also. He has started training with the team.
“It means we are more strong now than a few days ago and I’m absolutely sure we will give a good answer on the pitch.”