The Brazilian, one of the key parts of the French team's attack this season, picked up a thigh injury in a League Cup game at Saint-Etienne on Wednesday that will keep him out of action until mid-November.
"He is already out for the next three games. We will re-assess the situation during the international break," Lyon said in a statement.
The next batch of international games is scheduled for the November 11-15 period.
Lyon host arch-rivals Saint-Etienne in Ligue 1 on Saturday and entertain Real at their Gerland stadium on Wednesday. They were crushed 4-0 at the Santiago Bernabeu last week.
The seven-times French champions have been making do without the services of Argentine striker Lisandro Lopez, who has been out for eight weeks with an ankle injury. He is doubtful for Wednesday's Group D clash.
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