Real Valladolid played host to Villarreal in their opener and suffered a 3-0 defeat at home.
Being regarded as one of the early title challengers, Emery's side will look to go deep in this competition.
Dortmund started the pre-season on a positive note, winning their opening three games against Luner SV, Dynamo Dresden and Verl.
Liverpool defeated Villarreal 3-2 and won the tie 5-2 on aggregate to reach another Champions League final under Klopp.
Having already won the Carabao Cup final earlier in the year, Liverpool have also reached the final of the Champions League and the FA Cup.
Villarreal will host Liverpool in the second leg of the Champions League semi-final fixture on Tuesday.
Liverpool captain Jordan Henderson admitted their first goal was a “bit lucky” in the Villarreal win on Tuesday.
Let us look at the talking points from the one-sided encounter and what it means in the grand scheme of things:
Liverpool defeated Villareal 2-0 in the first leg of the Champions League semi-final fixture on Tuesday
Unai Emery’s side produced a defensive masterclass to secure upset victories against giants of European football.