Granada meet United in the first-leg of their quarterfinal tonight.
"We could surprise a few people for sure, we will fight until the end," Quina told the Daily Mail.
"We are a really passionate team, we have big dreams and goals - the manager makes us feel like everything is possible."
Unfortunately for Quina, he is ineligible for the games against United having joined Granada on loan from Watford until the end of the season.
He said: "I'm not going to lie, I am little bit disappointed. I like playing in the big occasions, against the big teams, in the big stadiums.
"I'd learn a lot because United are a top team with world class footballers - it will be a great experience for my team mates.
"But I'll be there supporting them. Granada is like a family, it doesn't matter (if I'm not playing) the team always comes first."