Owls boss Garry Monk said the 28-year-old is progressing well and could feature on the bench if required, but is unlikely to be risked ahead of the international break.
“He’s out on the pitch again today,” Monk said.
“We’ve had a good look at him and although he’s not yet in full contact he’s out there training and he’s ticking a lot of the boxes so we’ll see tomorrow.
“The weekend will probably be a bit of a push.”
Dominic Iorfa and Julian Borner seemed to have struck up an understanding in Lees’ absence.
Asked whether Lees’ selection would be worth the risk, given their form, Monk said:
“It won’t be. It might be more of being on the bench if we’re talking Saturday. We probably won’t risk it for the game, but he’s progressing well.”
Sam Hutchinson will miss the match through suspension after picking up his fifth yellow card of the season during Tuesday’s defeat at Hull, while Fernando Forestieri will serve the final match of his suspension.