Germany goalkeeper Rene Adler needs a knee operation and will miss the rest of Bayer Leverkusen's pre-season training, the Bundesliga club confirmed Tuesday.
Adler, who sustained the injury in a friendly against Red Bull Salzburg on July 3, will have the operation on Wednesday to remove degenerative patella tendon tissue from his right knee, DPA reported.
"An operation is unfortunately unavoidable if I want to play this season without any ongoing problems," said the 26-year-old.