Union Berlin might be top of the Bundesliga but coach Urs Fischer is still playing the underdog card. They host Borussia Dortmund on Sunday with the fifth-placed visitors needing a win to jump back towards the summit. Union lead the standings by two points with Dortmund another two further back. “I don’t want to assess who has the most the pressure,” Fischer told a news conference on Saturday. “Both teams will take to the field to win. We are playing at home. We will do everything we can to win this game, which will once again require an extraordinary performance from us. We have to play to th…