Carvalhal has operated a rotational policy at Hillsborough since taking over, and utilised 24 different players already, but Lees has been a mainstay in the side.
The former Leeds United defender has played in every one of Wednesday's 12 matches to date, and Carvalhal has been staggered by his fitness levels.
"Tom [Lees] recovers fantastically between games," the Portuguese boss said. "After two days, he is ready to play again which is why we are using him. It is unbelievable. His physical capacity is not normal.
“Secondly, he is a player who understands exactly what we want from the defensive part of the team and thirdly he is playing very well.”
Lees has already had to play alongside three different centre-back partners this term, but he has been a steadying presence in the backline.
The 24-year-old enjoyed a fine debut season with the Owls last term, and he appears to have simply picked up where he left off this time around.
Despite his great form, Carvalhal has not ruled out giving Lees a rest in the future, though.
“Probably in the future there might come a time when we will leave him out," he said.
Lees will be hoping that date is a long way off, especially as Wednesday are starting to show signs of real promise.
The Yorkshire side have won their last three matches in all competitions, and play host to Preston North End at the weekend knowing that a win could take them into the play-off spots.