A second-half goal from Alex Grimaldo sent Bayer Leverkusen to a 1-0 home win over Mainz, closing the gap with league leaders Bayern Munich to one point. Borussia Dortmund’s struggles in the league continued with a 4-2 loss at Holstein Kiel earlier on Tuesday, raising the heat on under-fire coach Nuri Sahin. In Leverkusen, Xabi