Niko Kovač contract extension at Borussia Dortmund 'only a matter of time'

Ahead of Friday’s Matchday 5 curtain-raiser with Werder Bremen, Dortmund sit two points clear at the top of the German top flight with four wins from as many league outings under Kovač and are the only team in the division with a perfect record. Watch: Kovač previews Bremen & gives latest on Schlotterbeck