Dudek out for six weeks with fractured jaw
The Polish former Liverpool player, making a rare start, was forced off just before half-time after colliding with Auxerre forward Roy Contout on Wednesday. A scan showed the extent of the damage, Real said on their website.
Dudek has had an eventful few weeks as he was one of four Real players fined over allegations Xabi Alonso and Sergio Ramos engineered deliberate red cards in last month's Champions League game at Ajax Amsterdam.
Dudek appeared to relay messages from coach Jose Mourinho to first-choice keeper Iker Casillas, who then passed them on to the two outfield players.