Chelsea have had a man sent off in all three of their defeats to the European Champions since 2000, and Lampard believes that they need to keep 11 men on the field if they are to stand any chance of winning tomorrow's game.
"Discipline is a huge factor at this level," he said.
"To play a man down against Barcelona is very tough. We have to tackle and close space, but we've got a good discipline in our team.
"Keeping 11 on the pitch is crucial."
The Spanish giants will be looking to become the first team to retain the Champions League since the change in format of the competition in 1992, while Chelsea are aiming to become the first London club to win the trophy, an accolade that Lampard believes the capital deserves.