German champions Bayern are heavy favourites to progress from the quarter-final tie having once again dominated domestically this season and been impressive in Europe.
Porto coach Lopetegui believes Pep Guardiola's side is one of the best Bayern teams in history, but has backed his players to cause an upset if they use the ball cleverly.
"'Ambition' and 'imagination' are two words we have in mind," he said. "I'd like to remind everyone that we didn't win a ticket to this competition [Porto qualified for the group stages via the play-offs] - we had to earn it.
"We are here, proud and happy to be playing among the best teams in Europe at this stage of the Champions League.
"We want to be the main performers tomorrow, while maintaining respect for our opponents. We are talking about one of the best Bayern sides in the club's history.
"Bayern have injuries but will still have seven or eight world champions on the pitch. We don't care about the players they don't have. We have to focus on the ones that will play."
Guardiola has paid tribute to the style of football employed by Lopetegui, and the 48-year-old returned to the compliment to his former Barcelona team-mate.
"I feel the same way Guardiola does about facing me," he added. "There is a lot of respect between us.
"Bayern want possession and usually they get it. We have to take good care of the ball, use it perfectly. We have to be great in attack and defence."
Lopetegui has been boosted by the return of top scorer Jackson Martinez, who has been named in Porto's 20-man squad for Wednesday's first leg.
