Pochettino will now allow his stars a few days off following this famous victory but urged them to finish the job when they travel to Germany for the second leg in March.
Pochettino continues to have to make do without Ben Davies, Dele Alli and Harry Kane, who are all injured.
"Always when we play this competition and against a good side like Dortmund it is very hard".
Mauricio Pochettino, the Spurs manager, refused to expand on what he called "rumours" but said he was not surprised by how well Sancho's career has developed.
'Next time Son scores I will go to the dressing room, have a shower and wait for the game to finish, ' Pochettino joked.More news: Danny Boyle's East Anglia film 'Yesterday' gets first trailer - featuring Ed Sheeran
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"But after we fixed some problems, showing them some clips at half-time and talking a little about different positions - offensive and defensive - and trying to help the team to perform better". 'He was fantastic again.
"They get a lot of money before they have played games". Always, when you play a very good side like Dortmund, it is hard and there is still lots of work to do'.
Pochettino's decision to pick Jan Vertonghen as a left wing-back against Dortmund paid off handsomely as the Belgian set up Son's opener before scoring the second goal himself. He smiles and he creates energy in every single game.
"I must say for these boys it's a test because they are rich before they play".
Dortmund were without the services of talisman Marco Reus as Chelsea-bound Christian Pulisic was drafted into the attack.