Brighton manager Chris Hughton is concerned that the Seagulls' excellent run to the quarter-finals of the FA Cup has come at a cost.
Hughton's side defeated Championship side Derby County 2-1 in Saturday's fifth-round tie thanks to first-half goals by Anthony Knockaert and Jurgen Locadia.
However, Hughton has revealed that veteran striker Glenn Murray, who scored twice in the fourth-round replay win at West Brom, is struggling with a calf injury while Davy Propper missed Saturday's match because of illness.
Lewis Dunk and Leon Balogun were not involved in the match because of injury so Hughton handed a first call-up to the squad for teenage defender Leo Ostigard.
Hughton said of Murray: "He just felt his calf very slightly, but certainly enough, the same with Dunky, for him not to be available.
"And then we will push as hard as we can to get them fit for the Leicester game (on 26th February).
"Glenn probably more so than Dunky would have been involved. I think Dan Burn has done very well in the games he has played.
"Davy [Propper] was ill, trained on Friday and then didn't feel great. We assessed him and he was definitely not well enough to play.
"It's unusual for us. Generally we've been good with injuries but it was a difficult week with Leon Balogun injured as well in training, his shoulder. Probably that makes the result even more pleasing."
Locadia picked up an ankle injury against the Rams while Florin Andone is suspended.
Brighton, 8/1 to be relegated this season, are available at 10/3 to beat Leicester and 16/1 to win the FA Cup.