Schalke lose top-scorer Serdar for rest of season
The 23-year-old Serdar, who has scored seven league goals this season from defensive midfield, suffered the injury in the second half in Sunday’s 3-0 home loss to Augsburg.
Serdar, who made his Germany debut last November, will undergo further tests to decide “whether an operation is necessary at the end of the week,” said Wagner.
Serdar is expected to be sidelined for from three to four months, missing their last seven league games.
For Wednesday’s league match at Fortuna Duesseldorf, who are third from bottom, France Under-20 midfielder Jean-Clair Todibo, who is on loan from Barcelona, is fit after recovering from an ankle injury.
The loss of Serdar is the latest blow to Schalke, who are winless in their last nine league games, conceding 22 goals and scoring just twice.
Having been in the title race before Christmas, Schalke have dropped from third in December to eighth in the table.
The pressure is mounting on ex-Huddersfield Town boss Wagner, who admits the situation is “not pleasant”, having also been hammered 4-0 at Dortmund ten days ago.
“At the moment we are no longer the team we were in the first half of the season,” said Wagner.
“You can’t compare the kind of football we played back then.”