The minute-starved duo will be given a chance to impress in the Champions League group stage clash, with United having already secured top spot in their group.
Asked about Henderson and De Gea, Rangnick said; "Well, to start, both of them will play tomorrow in the first XI.
"As you saw, Donny came on as a sub last Sunday and I know that Dean is a very, very good, ambitious goalkeeper.
"We definitely need two goalkeepers, we have even three with Tom [Heaton] and with [Lee] Grant we have a fourth one, so we have four goalkeepers.
"But I would say the three goalkeepers that really come into recognition for the first team. As I said, I have to get to know the players first in the next couple of weeks in order to finally assess them.
"Right now, I am more than happy to have all of them on board and I will try to give them as much game time as possible."