We take on the German giants - currently top of the Bundesliga - in Matchday One in Group H at Wembley Stadium, connected by EE.
La Liga champions and Champions League holders Real Madrid and APOEL of Cyprus complete our group and meet at the Bernabeu this evening.
"It's such an important game," said Mauricio. "To start well and take three points will be key. We're excited to start such a huge competition and we expect a tough game against Dortmund, a great team with experience in Europe.
"We need to be focused. It's like a final and we need to show that we can be competitive and go ahead (in the group).