Holders Barca, who won last month's Champions League last-16 first leg in Leverkusen 3-1, have conceded just five goals in 13 home La Liga games this season and let in only two at the Nou Camp in their three group matches in Europe's elite competition.
A big reason opponents find it so difficult to score against Pep Guardiola's side is that they rarely go a game without having the ball for at least 70 percent of the time, their mesmerising passing game grinding teams into submission.
In Europe's top five leagues, Barca playmaker Xavi has completed by far the most passes in the opponents' half this season with 1,553, Barca's website said.
Their World Player of the Year Lionel Messi, Champions League top scorer this term with seven goals, is second with 1,351 passes while full-back Daniel Alves is fourth on 1,215 - sandwiched between Real Madrid's Xabi Alonso with 1,271 and Arsenal's Mikel Arteta on 1,207.
"The fact that it is a tough prospect is clear to all of us but it's not over until it's over, as the saying goes, and we'll wait and see what happens," Leverkusen forward Stefan Kiessling said in an interview on the club's website.
"We want to go there and do ourselves justice and look for our chances."
"To win against Bayern is special," Leverkusen coach Robin Dutt said.
"If we continue playing like we have done in the past few weeks then the results will come.
"Of course it's going to be tough to win 3-0 in Barcelona but I don't think it makes any sense to think about that.
"First of all we have to play a good game, there will be 4,000 fans coming with us to Barcelona and whether we get through or not we owe it to them to play well."
