Dortmund x Liverpool
Liverpool are trained by Klopp. Klopp was the Dortmund trainer for 7 years, until last year. It surely is a big advantage. He knows their tactics(which have not changed much) and he knows every player...So this is really a huge advantage.
People take into consideration the big win of Dortmund over Spurs, in the previous round, but in that round Spurs used many subs..