Aston Villa captain Jack Grealish has been ruled out for around a month with a leg injury.
It is the first league game England international Grealish has missed for Dean Smith's side in 15 months.
"We will assess it as we go. It is certainly not a recurrence of an old injury and certainly not long term," Smith told BBC Sport.
"We will just assess it, I am an eternal optimist and I'll hope he is back for Leeds next week but I'll leave it to the medical staff."
Pressed for how long he thought Grealish would be out for, Smith added: "We don't believe it's a long-term injury.