The Portuguese forward, a big-money summer signing from Nacional, has started just once this calendar year, having recovered from a hernia problem.
Matias, who has netted twice in 13 appearances, was an unused substitute in Saturday's home defeat to Rotherham United.
Speaking at his press briefing today, Carvalhal said: "Marco is near to playing. He is near to playing.
"He had surgery. He had a big problem. At the beginning of the season, we played a different system.
"Since Marco has comeback, we have played a different formation that he has never played before. Playing 4-4-2 is a little different to him.
"He's working very hard and is more ready than he was two or three weeks ago. He's a player who could be involved in the 18 tomorrow."
Carvalhal has no fresh injuries to contend with as his Wednesday side look to halt their four-match winless run.
Sam Hutchinson is expected to start, having shrugged off a knee problem, while Lucas Joao is pushing for a first-team recall after an impressing second half showing versus the Millers.
The Owls are seeking to get their faltering promotion campaign back on track at fourth-placed Brighton.