The Brazilian defender is undergoing treatment on a torn calf muscle that forced him out of last weekend's victory over Peterhead.
Rangers boss Ally McCoist is already without Seb Faure and fellow defender Ross Perry, who are both sidelined for a number of weeks following hernia surgery.
After scans confirmed the extent of Emilson's injury, McCoist said: "Unfortunately it's not great. He has a first degree tear in his lower calf just above the Achilles and it looks like he will be out longer term too.
"It looks as though Ross has a hernia problem which will need operated on and that is going to be six or seven weeks sadly.
"So it looks as though we will be without these two lads for a number of weeks now.
"Sebastien will also be five weeks minimum so that's another problem.
"However, I felt Chris Hegarty and Lee McCulloch did well at the heart of the defence last Saturday."