The Argentine is the bookies' favourite to take over as United's next permanent manager despite Ole Gunnar Solskjaer's perfect record in five games as caretaker boss following Jose Mourinho's sacking.
Spurs, in third place, are 10 points ahead of their sixth-placed visitors and are just six points off leaders Liverpool.
Pochettino's men are still involved in four competitions despite working with a fraction of the budget on offer to Mourinho over the past two-and-a-half seasons.
"Of course when you're a manager or coach you cannot be focused on all the rumours," Pochettino said on Friday, referring to his meeting with Solskjaer being billed as a head-to-head for the United job.
"The most important thing is the motivation that we have to do our job in our best way. Of course Manchester is going to come on Sunday trying to win.
"Of course for him (Solskjaer) it's a massive motivation or challenge to manage Manchester United, like for me it's a massive challenge to be in front for this football club, Tottenham.
"Always the motivation is to win because we're so competitive. We're people that love to win and hate to lose, and always when you play a friendly game or a competitive game like Sunday always it's about winning."
Pochettino's achievements are all the more remarkable given Spurs have played in a makeshift home at Wembley for the past 18 months and did not sign a single player during the summer transfer window.
Tottenham are again unlikely to do business in January, with the immediate concern more focused on ensuring some of their best players do not leave.
Christian Eriksen has been in fantastic form of late but the Danish midfielder has yet to agree an extension on his contract that expires in 2020, sparking interest from a host of top European clubs.
"Christian is a very clever person and of course there's going to be a decision from him, from the club, from different parts and I hope he can be committed to the club long-term," said Pochettino.
"In football it's about timings, negotiations, different parties and how they feel.
"Of course, it's his right to wait, to sign this week or in six months, to have different dreams and challenges. For me, it's not a point to discuss. He's committed to us, he's playing so well. I'm so happy with him."
And Pochettino joked that he treats Eriksen in a similar way to his dog.
"Christian is a very special person and you need to give him freedom, like on the pitch," added Pochettino.
"You cannot put him in a box. You need to give freedom and trust him. Like my dog, in the park. I trust my dog. I say, 'Go, I trust you'".