Wilson has barely featured for Man United this term but he signed a new contract at Old Trafford earlier in the campaign.
Pereira, meanwhile, has had more luck having featured against the likes of Ipswich Town and Wolfsburg.
Van Gaal insisted the pair are in contention to be included against Middlesbrough but made them no promises.
“Yes, of course they are in the selection [the squad],” van Gaal said.
“But I have to select the line-up and that I don’t know. I have to do that on Wednesday.”
United would be wise to select a strong team to face Middlesbrough after the debacle against MK Dons last term but it would be good for supporters to see both Wilson and Pereira in action. Wilson, in particular, will be hopeful of featuring as he has often been overlooked so far this term.