Abdullahi picked up a hamstring injury against Burundi, while Collins is yet to feature for the Super Eagles in this year’s competition.
Having recovered from their setback to resume light training, the pair hope to recover in time to play a part in Nigeria’s Afcon title bid.
Rohr expressed his confidence both players will be in contention to feature in the tournament’s Round of 16 fixture.
“They are having special training sessions with the physios and I hope that they will be available for the next game [Round of 16] not this one [against Madagascar]," he told media.
“[Madagascar game] is too short and we don’t want to take any risk.”
Nigeria are already through to the 2019 Afcon knockout stage but need to beat Madagascar, or earn a draw, in their last group match to confirm their place as Group B winners.