Bayer Leverkusen will finally be able to properly celebrate the Bundesliga and German Cup titles with their fans on Sunday. The club were crowned Bundesliga champions for the first time ever in April, but players, coaches and officials had to hold back on celebrations because there was still a lot to play for in the season. On Wednesday, Leverkusen lost to Atalanta in the Europa League final, but defeated Kaiserslautern 1-0 in the Cup final to complete a domestic double and finally celebrate “as they want to,” sporting director Simon Rolfes said. “They’ve pulled through this season like this, …