The Blues desperately need a win to keep their play-off hopes alive.
Loan signing Lafferty has yet to make his debut for the Championship side having missed Saturday's defeat to Charlton after picking up a groin injury on international duty with Northern Ireland, the Mail reports.
Meanwhile, Toral did feature against the Addicks, and in fact gave the away side the lead just after the half-hour mark, but he had to be taken off during the opening minutes of the second-half due to impaired vision (via Mail).
And Rowett confirmed that the pair could now miss the game against the Seagulls.
"I would imagine Jon is a doubt, for Kyle it’s a very, very quick turnaround, whether he’s going to be fit I would probably doubt," he told the Mail.
If neither man is able to prove their fitness in time, it will be a major setback for the club. The loss to Charlton dealt their play-off hopes a huge blow, as while they still boast a game in hand over Derby who sit sixth, they now find themselves eight points adrift of the Rams, and are running out of time to make their charge.
And without Toral or Lafferty, their task of building some momentum in their next game will be much tougher given that Chris Hughton's men are still well in the mix for automatic-promotion.