The Spanish side qualified for the knockout stages by winning a group that also contained seven-time winners AC Milan. They also managed to find the net six times from three away outings.
Discussing this evening's tie with UEFA's official website, Spanish youngster Isco admitted that Los Boquerones would need to carry on their positive goalscoring form against Porto to stand a good chance of reaching the quarter-finals.
"They're serious opponents, but we have lots of confidence in our ability and we have nothing to lose," he said. "In a two-legged tie it is important to score at least one away goal. We will play as we always have, defending well, trying to get a goal and a good result.
"The outcome depends on many things. There's luck involved too, but I trust my team. We have to take it step by step. Things will happen."
Isco has scored two goals in the competition so far this season.