Many observers make Barça favourites to beat the Blues and advance to their third Champions League final in four seasons, but Kalou is adamant Pep Guardiola's defence has enough flaws to offer hope of eliminating the holders.
While Barça's strength lies in the world-class skill of Lionel Messi, Andres Iniesta and Xavi, Côte d'Ivoire star Kalou is less impressed with their back four.
"They have their weaknesses," Kalou said. "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. 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. Our fans expect us to win, we expect to win."
Although Barcelona are rightly regarded as Europe's pre-eminent force at present, Kalou points to their failure to keep pace with Jose Mourinho's Real Madrid in La Liga this term as proof they are not invincible.
"Everyone forgets that Madrid are having a great season with Jose," Kalou said. "Right now, if we had played Madrid, people would not say that Chelsea has no chance.
"But, because it's Barça, 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."