"It will be a very difficult game in London," he insisted. "To get through to the final we will have to make an heroic effort. It will be difficult, but this Barca side is capable of everything."
Barcelona are chasing a famous treble and lead La Liga by seven points with four matches to go.
But striker Samuel Eto'o, La Liga's leading scorer with 27 goals, says his side must retain their focus for the rest of the season.
"We still aren't the champions. We have to treat the other teams that are coming up with respect," he said.
"But it's true Madrid need a miracle to stop us. Now we have to forget about this win and think about Chelsea, where we must go out with the same desire and with humility, as if this match didn't happen."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.