Lionel Messi-inspired Barca are odds-on favourites to win their latest Champions League clash with the Blues and reach next month's final in Munich.
Kalou said: "Our fans expect us to win, we expect to win. They have their weaknesses. We know that they haven't been so confident at the back, conceding a lot of goals, so that is something we can play on."
He added: "People see the way Barcelona play today and they can say, 'Chelsea have no chance against Barcelona'.
"But, as a player for Chelsea, we work hard every day in training and we believe that on the pitch is the only way of answering all those negative thoughts."
Despite powering into the Champions League semi-finals, Barca are not even top of the Primera Liga, with Jose Mourinho's Real Madrid leading them by six points.
Kalou said: "Everyone forgets that Madrid are having a great season with Jose.
"Right now, if we had played Madrid, people would not say that Chelsea has no chance.
"But, because it's Barca, because they have Messi and all those players, people are thinking that we can't make it.
"The Chelsea players know that this is one game and, in one game, everything can happen."
Source: PA
Source: PA