Goalkeeper Sam Johnstone and midfielder Alex Mowatt are suspended after they were sent off against Cardiff last Sunday. Semi Ajayi has gone on international duty with Nigeria, and loan duo Matthew Clarke and Jayson Molumby are unable to play against their parent club.
Ismael said,“You can complain about who cannot play, or you can focus on the fact it’s an opportunity for other players to come in and play.
“We can have another picture in terms of our squad, but we have shown already in the first six months that we can be flexible with players in certain positions.
“What is important is that the players who are on the pitch will know their job. They know what they have to do and I’m looking for a strong performance.
“It’s a great chance for the players who play on Saturday to show what they can do.”
Daryl Dike, signed at the start of the month from Orlando City, is being prepared to make his Albion debut against QPR on January 15 and is not expected to feature against the Seagulls, but Matt Phillips could feature after recovering from a hamstring injury.
He said: “The FA Cup is such a traditional competition here in England. The first game I played in when I came to England was for Crystal Palace in the FA Cup. It was a great feeling and it was special.
“Everything is possible in one game. It’s great to be part of it and it’s a great opportunity for us to compete against a Premier League side and to see where we are and where we want to be.
“It’s the right game for us. It’s good to have a change of focus sometimes and this game on Saturday gives us that.
“We have to be relentless out of possession and press with intensity because we know that Brighton will try to have more possession than some of the teams we come up against in the Championship.
“I’m looking forward to assessing our situation against a Premier League club.
“As a manager and as a player, I always wanted to compete with the best. You can only improve and get better when you come up against the best.
“It’s the next step in our development as a team and a club, coming up against a team in Brighton who have a clear way of playing.
“They are now an established club in the Premier League and they’ve had a great season so far.”
Brighton defender Adam Webster is likely to miss the visit to The Hawthorns.
The centre-back, who played the full 90 minutes in last Sunday’s 3-2 Premier League win at Everton, is suffering from fatigue.
Seagulls captain Lewis Dunk remains sidelined by a knee injury and Mali midfielder Yves Bissouma is unavailable due to his participation in the Africa Cup of Nations.
Danny Welbeck could make his first start since returning from a three-month injury absence but fellow forwards Jurgen Locadia and Aaron Connolly were this week allowed to leave the club.