“Ethan comes into the picture, Phil Jagielka comes in to the picture, a change of shape might come into the picture," said Wilder.
"Ethan is going to play a big part in our season. There's some decisions to be made."
Sunday's game will be the first top-flight clash between Sheffield United and Leeds since 1994.
“We've had some fabulous games with Leeds United over the years," said Wilder.
"It'll be great for both clubs to battle it out on Sunday afternoon."