The Owls are set to strengthen their defensive ranks ahead of Saturday's visit of Leeds United.
Lees, who came through the ranks at Elland Road before switching to Wednesday in 2014, sat out Tuesday's defeat to Burton Albion through injury.
Midfielder Jose Semedo was forced to partner Sam Hutchinson in the absence of both Lees and captain Glenn Loovens, but was withdrawn before half-time the Pirelli Stadium with an injury of his own.
Semedo's departure forced left-back Daniel Pudil into an unfamiliar central role, with his place taken by right-back Liam Palmer in turn.
However, keen to avoid a repeat of Tuesday evening, Carvalhal told BBC Radio Sheffield that a defensive recruit is imminent ahead of Leeds' visit.
"Very soon we will be with four central defenders," he said, adding that Loovens is 'not dead' and 'knocking on the door' after returning to training.
"Absolutely, I'm sure. In a few days - maybe a few hours."
The Portuguese did not confirm the identity of the new addition, however, and refused to be drawn on reports linking Wednesday with a return for Braga's Vincent Sasso, who spent last season on loan at Hillsborough.
The Owls were also linked with a move for Preston North End captain Tom Clarke earlier in the week (Mail).