Joao arrived at Wednesday from Nacional last summer, and he has struggled for consistency during his first season in England.
The Portuguese striker made an encouraging start to life at Wednesday, but he has gone on to hit the back of the net just once in his last 23 appearances.
The 22-year-old has generally been utilised as a substitute, but Carvalhal insists that he has made good progress.
CC: Joao has done a lot of growing up. He arrived as a kid from Portugal and is now a man. He is a better player #swfcLIVE— Sheffield Wednesday (@swfc) April 18, 2016
Joao has already racked up 36 Championship appearances for Wednesday this season, with the Yorkshire side showing faith in the powerful forward.
He could feature again against Milton Keynes Dons on Tuesday evening, as the Owls aim to further consolidate their place in the play offs.
Wednesday are currently sit five points clear of their nearest rivals for a top six place, Cardiff City, with just four games remaining.
The Owls are also boosted by the news that most of their squad have made it off the treatment table, giving Carvalhal plenty of options to choose from.