Bayer Leverkusen have added the German Cup title to their Bundesliga triumph and completed their maiden domestic double with a 1-0 win against second division team Kaiserslautern on Saturday. Granit Xhaka scored the winner in the 16th minute with a stunning long-distance shot after a sloppy clearance from the Kaiserslautern defence. Leverkusen were down to 10 men since the 44th minute as Odilon Kossounou received a second yellow card for a foul on Boris Tomiak. But Kaiserslautern weren’t powerful enough to capitalize on their numerical superiority, despite an incredible support from their trav…