Kelly has been suffering with a calf injury picked up in the 3-0 win over Bristol City while Ward sustained an ankle and shin injury in the early stages of last week's loss to Wolves.
Neil Redfearn had hoped both men would be fit to make the journey to Ewood Park, but is unlikely to risk them with a vital period of fixtures on the horizon.
On Kelly, the Millers boss said: "He's not far off, he might be struggling for tomorrow but hopefully for Tuesday he is back fit and available.
"Obviously calves are difficult injuries to judge and what we are mindful of is getting him back and that's it.
"What we don't want to do is to lose him for another four or five games if we bring him back too early.
"He is an important player for us, we know that, but we are mindful that when we get him back, we want him back."
Redfearn added: "Danny's struggling a little bit. He got a kick on his shin on the side of his leg.
"He is having some problems with it. It has settled down a lot, but again, he's another on that is a doubt for tomorrow.
"I am hoping it might settle down in the next three of four days, so he is another that might be available for the Huddersfield game."
The Millers do have some positive news, though, as Joe Mattock is set to resume at left-back after overcoming a hamstring problem, while the injury suffered by Matt Derbyshire in training on Thursday is not expected to rule him out against his former club.
"Joe is back training and comes into contention which is obviously a plus because he's a good and experienced player," Redfearn said.
"Matt got a kick in training, but it's just a kick, I think it will be fine. It's one of those things that happens in training."
Striker Leon Best serves the final instalment of his three-match ban, meaning Jonson Clarke-Harris could lead the line on his own.
Meanwhile, defender Richard Wood is back at the Millers receiving treatment for an abductor injury he has sustained while on loan at Chesterfield.
The centre-half has played five times for the managerless Spireites.
