Bundesliga champions Bayer Leverkusen battled past second-tier Kaiserslautern 1-0 on Saturday to win the DFB-Pokal and secure the club 39;s first domestic double. Leverkusen missed out on a treble after losing 3-0 to Atalanta in the Europa League final on Wednesday, in what was astonishingly their first defeat of the season in all compet .