The club's record striker missed Saturday's win at Bolton with a foot injury, but has returned to training this week after an injection.
Ladapo is not 100 per cent fit, but will play through the pain.
Assistant boss Richie Barker said: “He is OK, he trained and Tuesday and Thursday.
“Like most professional footballers at this time, he is not 100 per cent.
“He has completed both training sessions so it is good to have him back.
“When we were told we were certain it wouldn't be going into weeks or months, providing he reacted to the treatment he had and we he did we were pretty certain we would get him back within days.
“It will never be 100 per cent, it will be one of those things that you just have to grin and bear it.”
The Millers will also have Chiedozie Ogebene back available after he came off at half-time at Bolton.
The winger was fatiguing after a heavy shift in midweek, but is fit and raring to go.
Barker added: “He has trained as well, trained Tuesday, Thursday, all being well he will be available for selection.
“He is a big part of what we do. His pace is a major threat and he gets us up the pitch.
“It is a difficult ask we give him in terms of the physical output so we just have to manage him.”
Shane Ferguson (foot) is also expected to return to the fray after several weeks out while Mickel Miller, who has served a three-match ban, picked up a hamstring injury in training and is a doubt.
Crewe manager David Artell comes to familiar surroundings, returning to the club he represented as a player.
The Rotherham-born defender won promotion with the Millers in 2001 and his family worked at the club during the 1990s and 2000s.
He played at the AESSEAL New York Stadium in 2013 for Paul Warne's testimonial.