Cypriot champions APOEL Nicosia make up a fiendish group.
"I think tomorrow is so important, to start well in the competition and get the three points".
For Spurs, the game will also set the tone for the rest of the competition, something Pochettino alluded to on Tuesday.
Spurs were beaten 2-1 by Monaco at Wembley in their first group game a year ago and never recovered, and Pochettino said: "Last season after the first game at home against Monaco, it was hard to change the dynamic".
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"Last season, after the first game at home against Monaco, it was hard to change the dynamic".
"It will be tough because Dortmund is a great, great team but in our mind our mentality is to try to win and be aggressive from the first ball".
The 28-year-old kept his 5.3million followers updated of his journey with a selfie alongside the caption "let's go" before pinning his location at Wembley Stadium. Harry Kane admits that home form will be key but insists that the players are excited about the challenge.
Pochettino said that defeat had more to do with his team trying to win the Premier League title than any difference in quality between the sides. "You've got to see where you are". Pochettino's team are like a train, who tend to start with reluctant creaks and jerks before building-up a head of steam in late autumn.
The Argentine manager also said the Dortmund game, which is due to played on Wednesday (September 13), is "so important" for his side who comfortably beat Everton 3-0 in the Premier League over the weekend.
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Facebook said it was cooperating with inquiries by Congress into whether Russian Federation sought to influence the election. The company said $100,000 (£77,000) was spent on about 3,000 ads over a two-year period, ending in May 2017.
Pochettino hinted he could hand a debut to right-back Serge Aurier, a recent signing from Paris Saint-Germain, but Dele Alli is suspended after a red card in the Europa League last season.
"Last season was our first experience in the Champions League..."
In Spain or Italy they prioritise the Champions League rather than the domestic league.
There are, however, reasons to be optimistic. "In the last few games we've played at Wembley, we've played well and deserved more".
"With Wembley, we need to adapt our game", said boss Mauricio Pochettino. We've got to perform on the big stage.
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But she said Trump has proposed policies "that would hurt North Dakota's economy", such as cutting crop insurance. She thanked North Dakotans for their past support, noting, "you treated us very, very well in November".
"That's England, that's the culture and we have to be clever to find a different way to be competitive".