Both were helped off during last Saturday's PRO12 semi-final win against Glasgow Warriors at the RDS, with O'Driscoll hit by a back spasm.
The bad news is that D'Arcy, who suffered a recurrence of the calf muscle injury that has dogged him in recent weeks, will miss the showpiece match and is also "highly unlikely" for the following weekend's PRO12 final.
The good news comes with the fitness report on O'Driscoll.
"Brian is a lot more comfortable," said head coach Joe Schmidt. "His back tightened right up and he was unable to stretch out at all. It has happened a couple of times over the last three to five years.
"Therefore that's something that's come right within 48 hours before so he's a lot more comfortable now. If he's training then you'd expect him to be right for Friday."
Sean O'Brien, rested against Glasgow because of his own calf problem, has been declared fully fit while Schmidt also dismissed concerns about Richardt Strauss (knee) and Cian Healy.