Bundesliga champions Bayer Leverkusen completed their first domestic double with a 1-0 win over second division side Kaiserslautern to win the German Cup football title. Leverkusen missed out on a treble after losing 3-0 to Atalanta in the Europa League final on Wednesday. Granit Xhaka scored a powerful shot from 20 metres in the 16th minute of the final played at Berlin's Olympic Stadium to give Leverkusen a 1-0 lead. A minute before half time, Leverkusen were forced to play with 10 men after Odilon Kossonou was booked for a second yellow card.