Bayer Leverkusen are the favourites and aim to end a three-decades long wait for silverware but the fact that two duels between second division teams kick off the German Cup quarter-finals this week highlights how wide open the 2023-24 competition is. The last team from the remaining eight to lift the trophy were VfB Stuttgart, in 1997. And with Stuttgart next week visiting Bundesliga leaders Leverkusen, who have not earned silverware since winning the Cup in 1993, no more than two top tier clubs can reach the semi-finals. The only other remaining Bundesliga team are Borussia Mönchengladbach b…