Liverpool manager Jurgen Klopp faces Dortmund reunion in Europa League
Klopp, 48, left Dortmund last summer after leading them to the 2011 and 2012 Bundesliga titles, plus the 2013 Champions League final.
Holders Sevilla, meanwhile, face an all-Spanish clash with Athletic Club while Villarreal take on Sparta Prague and Sporting Braga face Shakhtar Donetsk.
Sporting Braga (Portugal) v Shakhtar Donetsk (Ukraine)
Villarreal (Spain) v Sparta Prague (Czech Republic)
Athletic Bilbao (Spain) v Sevilla (Spain)
Borussia Dortmund (Germany) v Liverpool (England)