The Ivory Coast international scored twice when the Blues beat Atletico 4-0 a fortnight ago, and he will be hoping for a repeat performance when they play in Spain on Tuesday.
Didier Drogba has been suspended for the opening three UEFA Champions League games so far this term, but is expected to return to the starting line-up for the next Group D clash.
However, Kalou has struck a fine partnership with Nicholas Anelka in Drogba's European absence, and he hopes to have done enough to justify a starting berth.
"It is good to be back on the pitch and scoring goals," he said. "As a striker it gives me a lot of confidence.
"Against Madrid we knew it was important to run behind their defence because they always try to play the offside line so when Anelka dropped deep it gave me the time and space to arrive in front of goal every time.
"So it was a good combination between me and Anelka and it paid off because I scored two and could have scored more.
"But in the end it is good enough that I put two in the net. At the start of the game I played behind the striker on the line-up but the thing is Anelka and I can always switch positions.
"It doesn't matter who is in front or who drops back, there is always a good combination.
"I suppose it happens because he is the kind of player who likes to go to the ball and I like to run beyond the defence sometimes so it gives us a choice of who plays behind."