The Wolverhampton club host the bottom-of-the-table Latics at the Molineux on Sunday in desperate need of a win as they sit 17th themselves but may be without leading scorer Fletcher who has been sidelined with a calf injury.
However, McCarthy has hinted that there is a slight chance the Scotland international may play some part.
"Fletch trained today with the squad for the first time and he did ok," he said.
"If he is right, he will be involved on Sunday.
"We are aware of the contribution he has made. But we will wait and see how he is before making any decision.
"The last thing we want to do is rush him back for this game and then repent at leisure during the two weeks of the international break."