Paul Trollope is hopeful that Pilkington may return for the trip to Yorkshire but is making no promises.
He said: “Pilkington has missed a lot of this week’s training with that thigh injury. It’s a muscle issue and he will be assessed at lunchtime today.
“It’s looking doubtful for Rotherham and we’ll have to wait and see for Derby, we’ll take it hour by hour.
“He’s a big player for us and we’ll miss him, but it gives someone else a chance to impress.”
There are a few more injury doubts for Saturday, with both Kadeem Harris (ankle) and Aron Gunnarsson (calf) missing parts of training this week.
Frederic Gounongbe is also a concern after sustaining an injury against Leeds.
Trollope said: “ Guonongbe took a stud to the achilles in that match, so we’ve got a few injury concerns going forward - particularly in attacking areas.”
“But that’s what the squad is for, if people are missing, then an opportunity knocks for someone else.”
New signing Joe Bennett is yet to make his Bluebirds debut, but Trollope was upbeat about the former Aston Villa man’s fitness.
“Joe has been working hard to get back to full training. His calf hasn’t settled down as quickly as we would have like, but he should be training with the squad by next week.”
Stuart O’Keefe has been missing for over a month now, and Trollope has some uplifitng news about the midfielder.
He said: “Stuart has been training fully for the last ten days or so and we’re really pleased with his progress.”
Rotherham captain Lee Frecklington will start against Cardiff in the Sky Bet Championship.
The influential midfielder has come off the bench in the last two games following a calf injury but boss Alan Stubbs has confirmed he is now ready to start.
Right-back Darnell Fisher returns from a one-game ban and will replace Stephen Kelly, who has a thigh problem, while on-loan midfielder Tom Adeyemi is unavailable against his parent club.
Striker Dexter Blackstock is likely to be in the squad as he builds up his fitness following his free transfer a fortnight ago, though a place on the bench is the best he can hope for.
Match Officials:
Referee: David Coote
The assistants are: Shaun Hudson and Tony Peart
Fourth Official: Darren Handley
Rotherham v Cardiff City
New York Stadium
ko 3:00pm.