The Germany defender limped out of Tuesday’s 4-2 German Cup win at home to Werder Bremen and a scan has revealed a torn groin.
Leverkusen are second only to runaway leaders Bayern Munich in Germany’s top flight after losing just once in their last 19 games in all competitions.
The 28-year-old, who made the last of his 19 appearances for Germany in 2014, has played in 15 of Leverkusen’s 21 league games this season.
The right-back has been the cornerstone of Bayer’s defence.
At the end of January, Bender extended his Leverkusen contract until 2021, but is now set to miss their forth-coming league games against Hertha Berlin, Hamburg and Schalke 04.
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