Brighton have doubts over Tomer Hemed, Connor Goldson, Anthony Knockaert and Steve Sidwell as they bid to overturn Sheffield Wednesday's two-goal lead.
All four were injured in the first leg and, although Lewis Dunk will return from suspension, Dale Stephens is still banned and Bobby Zamora (hip) is out.
Wednesday, who won 2-0 at Hillsborough on Friday, have no fresh injury worries ahead of the second leg.
Manager Carlos Carvalhal could decide to name an unchanged side.
The two sides drew 0-0 when they met at the Amex back in March.
Brighton forward Sam Baldock told the club website: "We've got nothing to lose now and the pressure is completely on them.
"We're positive and we're going to go for it. We've got 90 minutes for them to come to the Amex with a full stadium, with screaming fans egging us on.
"Stranger things have happened. I came off the pitch thinking, 'Come on, bring on Monday,' because believe me, this tie is not over."
Sheffield Wednesday manager Carlos Carvalhal told the club website: "We are absolutely and 100% focused and ready to go.
"As far as we are concerned, the score is 0-0 when we kick off on Monday. Brighton are a dangerous opponent, and they know what they must do.
"But we do also. And we are feeling good, feeling fresh mentally and physically.
"We will prepare for this game exactly the same as every game we have played this season. There is no other way.
"I do not even think about the final. I think 100% about the second leg and we are going to Brighton to give our absolute best."