Summer signing Ferguson could miss a third successive game with a foot injury that he picked up on recent international duty with his country.
Meanwhile, Ladapo has also picked up a problem in his foot and has gone for a scan.
On Ferguson, Warne, speaking at his pre-match press conference, commented: "I think Saturday might be too soon. He was out on the grass with the physio today (Thursday).
"He said he was virtually pain-free, which to me means he's training tomorrow and playing Saturday. But I always get told off for being too optimistic too early."
On the situation with Ladapo, the Millers chief continued: "He's hurt his foot. He missed training this morning and has gone for a scan. We'll know the severity of the injury soon.
"At the moment, I am doubtful he will play a part this weekend. He looked in discomfort today. You never know. He might get a really positive result back off the scan, feel better later today and be able to train tomorrow."
Defender Wes Harding, who missed the midweek game at Lincoln due to Covid contact, should be available for the trip to the north west,
Warne said: "I have been led to believe he is available this weekend, so hopefully he should be in the squad to travel. He is not ill and is healthy and should be available for selection."