We take on the German giants - currently top of the Bundesliga - in Matchday One in Group H at Wembley Stadium, connected by EE.
Retail details - third kit available at Wembley
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). First of all, we need to be better than Dortmund.
"In theory, it's Real Madrid first and then Tottenham, Dortmund and APOEL to compete to be second. That is theory - but football isn't theory, it's about trying to play and trying to win. Our ambition is to win every game."
We returned to the Champions League last season but were stung early by AS Monaco in our opening group game at Wembley. Of course, the French side went on to win Ligue 1 and reach the semi-final of the Champions League.
However, Mauricio feels we were always chasing the group from that stage. "Last season after the first game against Monaco it was difficult to change the dynamic (of the group).
"We know the first game is so important and we will try to win. It will be tough because Dortmund are a great team but our mentality is to be aggressive from the first minute and try to win.
"It's a tough group but all we're thinking about is trying to win this game."