Mario Gotze scores twice as Bayer Leverkusen extend Bundesliga lead . He also sets up first goal for Mario Gotze in 3 -1 win at Bayer Leverkusen . Leverkusen fall 13 points behind and drop to third place on goal difference . Dortmund , seeking first German league title since 2002 , have 15 wins from 15 matches .
Kevin Grosskreutz scores twice as Borussia Dortmund extend Bundesliga lead . He also sets up third goal for Mario Gotze in 3-1 win at Bayer Leverkusen . Leverkusen fall 13 points behind and drop to third place on goal difference . Dortmund , seeking first German league title since 2002 , have 15 wins from 18 matches .