Bayer Leverkusen inisist they are only looking ahead at Tuesday’s German Cup match against VfB Stuttgart and have not set their sights yet on Saturday’s Bundesliga topper against Bayern Munich. Leverkusen won 2-0 at bottom side Darmstadt in the league on Saturday to retain a two-point lead over Bayern and enter what could be a defining week with confidence. Xabi Alonso’s men are the only unbeaten side in all competitions in Europe’s top five leagues, with 25 wins from 29 games played so far this term. They have won 16 of their 20 Bundesliga matches, their first three in the German Cup and all …