Sheffield Wednesday are still battling to confirm their play off spot.
As one of Wednesday’s main attackers, there was surprise when Forestieri was withdrawn with the score locked at 1-1 at the iPro Stadium.
However, Carvalhal has defended his decision, by suggesting that he did not want to risk his star man getting suspended.
Forestieri was harshly booked during the second-half of Wednesday’s match against Derby.
And Carvalhal said: “I appreciate the personality of Fernando because even with this again and before and before and before, with kicks and so on, he is still playing the same way with offensive aggression. He goes to the defenders and I appreciate that in my player. Usually the players in these conditions will protect themselves but Fernando never does this.
“It is why I must substitute him (at Derby). Because these kind of things have a big influence on the dynamic of the team. Fernando is playing well but in the last 10 minutes I must protect the player because if he has a similar situation and a second yellow card, he will finish the season.”
Wednesday still have work to do, if they are to make it into the play off places this season.
The Owls are currently four points clear of Cardiff City, but they are due to face that Bluebirds this weekend.
If Wednesday can avoid defeat their place in the top six will be assured, but a Cardiff victory would put them under serious pressure.
Wednesday face mid-table Wolverhampton Wanderers on the final day of the season.
If the Owls do make it into the play offs, they are likely to face the side who misses out on automatic promotion - with Burnley, Middlesbrough and Brighton & Hove Albion all currently competing for the top two spots.