Teams are limited to 17 non-locally trained players in the competition, and Spurs have 20 in their first team squad, so Foyth, Georges-Kevin Nkoudou and Vincent Janssen have been unavailable throughout the group stage.
A draw and victory against PSV revived Tottenham's prospects, showing the resilience that has Pochettino's side in third place in the Premier League only five points behind Manchester City.
He said: "I always try to work hard, even when it's difficult". "It's a mistake that we made that at this level of football we can not repeat again. We need to arrive that way in Barcelona".
"Now, there is still one game to play and it is going to be tough". Of course now that is the problem and it's so painful to have players out of the list.
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But Eriksen, surprisingly dropped to the bench by Pochettino, came to Tottenham's rescue when the substitute fired home to take their Group B qualification bid down to the final game. "They're not going to have one day off until January".
The Argentinian is hoping Dele Alli can step up to the plate again, given his knack for producing the goods in big games. "His mentality is that he gets bored quickly when he doesn't feel the pressure". When he is alone with the ball in front of the goal he is bored.
"He's a competitor, he loves this type of game. But we have belief and faith that we can win", Pochettino said.
"It is a decisive game, it is a must-win game".
Those results mean that Spurs approach Sunday's clash in optimistic mood and ahead of the much-anticipated clash on Sunday, Alderweireld has claimed that the north London derby is the biggest in world football.