Lopetegui knows they're underdogs, particularly with Lionel Messi again amongst the goals.
"Barca are a great team and they have Messi too," said the former Spain and Real Madrid man. "We will try to face them while being recognisable (as ourselves), but taking everything to the limit to stop Messi and the rest.
"We will not think about anything that's not the game, the team, the level and the demands that an opponent like that means. We're focused on being capable to answering this great challenge of facing Barcelona, who are strong again and have clear signs of their identity."