Cooper missed Saturday's 2-0 win at Huddersfield Town with a calf strain and Whites head coach Marcelo Bielsa confirmed on Monday that the centre-back would not be fit for the clash against the Tigers.
Phillips, though, will return from a one-match ban for accumulating five yellow cards and the 24-year-old will definitely start with Bielsa still deciding who will drop out.
Providing his latest team news at Monday afternoon's pre-Hull City press conference, Bielsa said: "There's no news. Cooper is out of the group, Phillips comes back, that's all."
Asked if Phillips would come back into the XI or on to the bench, Bielsa said: "He comes back to play. There is someone who is going to leave the team but I have not decided who yet."
Adam Forshaw (hip), Tyler Roberts (hamstring) and Jamie Shackleton (muscle) also all remain out injured.