BERLIN, Aug. 3 (Xinhua) -- Leverkusen will have to kick off the season without their central defender Oemer Toprak, who suffered a thigh injury during a friendly, the "Werkself" announced via the club' s official homepage on Monday.

The Turkish international suffered the injury during Sunday's 3-1 win in a friendly over Italian outfit Chievo Verona. Coach Roger Schmidt already suspected that "this won't be a short-term problem", and he proved to be right, as Toprak sustained a tendon rupture in his left thigh, which was diagnosed following an MRI scan.

The 26-year-old defender will immediately begin with the rehabilitation process. He will be sidelined for a longer term nonetheless.

Toprak has been a part of the "Werkself" since July 2011 and became a key player in their defence. He made 110 Bundesliga appearances with two assists and three goals.

Bayer Leverkusen will face Hoffenheim at the first round in Bundesliga on Aug. 15.