B. Dortmund is leading the Bundesliga this year by a wide margin - they have not lost at 12-3-0 thru 15 matches.
We played them twice last year in CL Group H beating them 3-1 and 2-1 but the seem to be playing a lot better this year. Although they had a pretty easy Group stage edging out A. Madrid (3rd in La Liga) for the group winner on a tiebreaker and the other 2 clubs were Club Brugge (2nd in Belgian 1st Div.) and Monaco (19th in Ligue 1).
They had 7 players called up to World Cup.
FW Marco Reus - Germany their leading goal scorer
DF Raphael Guerreiro - Portugal
MF Thomas Delaney - Denmark
DF Manuel Akanji - Switzerland
GK Roman Burki - Switzerland
MF Shinji Kagawa - Japan
DF Lukasz Piszczek - Poland
Their second highest goal scorer is Spaniard FW Paco Alcacer