Neal Maupay and Henrik Dalsgaard will certainly miss Brentford's west London derby with Fulham, while Florian Jozefzoon is likely to be absent.
The Bees striker is suspended after picking up his fifth yellow card in the 2-2 draw at QPR, while the Danish full back is still absent with a heel injury.
Jozefzoon, meanwhile, picked up a hamstring strain early in the contest and, as of Thursday morning, has not trained with the squad meaning he is highly unlikely to feature.
“Flo felt his hamstring and we had to bring him off (at QPR),” Smith said.“He's a doubt for Saturday.”
He added: “He hasn't trained yet. He's having a scan this afternoon so we'll see later.”
Dalsgaard's heel injury is preventing him from taking part and it appears to be a longer term issue as things stand.
Smith added: “He won't be ready. It's a low burner, a bit like the Lasse Vibe one. It's dragging on a bit”
Maupay picked up a yellow card for a late foul in the win at QPR and, as such, will sit this game out.
Smith confirmed: “Neal Maupay won't be involved as he picked up his fifth booking. I spoke to him before him going on not to get booked.
“He picked up his fifth and the 19th game was the one where it goes up to 10. It happens and you deal with it. But Lasse Vibe looks on fire again and he's scored a lot of goals under my tenure.”
The Frenchman's suspension could provide a chance for Justin Shaibu to impress during the contest, even though he's been a forgotten man in recent weeks.
Smith explained: “Justin has done all right when he's been on the bench. He's still a member of the first team squad but he hasn't had the opportunity. He's fine.”
Alan Judge is moving closer to a return but the game will come to early for him as Smith wants him to feature for the B team first.
The head coach revealed: “He's very close. We've done some 11 v 11 today and Alan is involved in that but Lewis can get on the pitch now.
“Until Alan plays minutes in terms of a B team game or behind closed doors (then he won't be considered for selection).”
Rico Henry (knee) is a long term absentee.