Union Berlin suffered a first season defeat on Saturday but retained the Bundesliga lead because Borussia Dortmund also lost a week ahead of their prestigious duel with Bayern Munich. Dortmund fell 3-2 in Cologne after leading 1-0 from Julian Brandt. The hosts hit back within three minutes after the break from Florian Kainz and former Dortmund player Steffen Tigges, Dejan Ljubicic got their third, and Tom Rothe a late second for Dortmund. Union lost 2-0 at Eintracht Frankfurt but are still top, on goal difference over Freiburg who won 2-1 against Mainz. Bayern and Dortmund are two points back …