The first-ever competitive meeting between Milan and Atletico saw Diego Simeone's men clinch a narrow victory at San Siro on Wednesday night thanks to Diego Costa's last-gasp goal.
The Rossoneri had dominated the game, with Kaka and Andrea Poli both going close to scoring while on-loan QPR forward Adel Taarabt impressed on his Champions League debut.
Kaka was easily Milan's most dangerous player, the former Real Madrid man rattling the crossbar and heading against Thibaut Courtois from close range.
Despite the fact his evening ended in frustration, the Brazilian playmaker is staying upbeat.
"We had chances to score and I don't like to talk about being unlucky, we need to be more precise," said Kaka.
"The only thing we were missing was the goal, we played well and we prepared well but it was Atletico who scored in the final minutes.
"I'm optimistic after what I saw.
"We'll try and play our game in Madrid. It's not the result that we were after but we have time to improve and to learn from this match."
Milan head coach Clarence Seedorf is confident he now knows enough about Atletico's game to overturn their slender advantage when the sides reunite in the Spanish capital.
Seedorf has already travelled to the Vicente Calderon to assess his club's last-16 opponents from the stands and, having now seen them in action close up, he reckons they can be beaten.
The Dutchman told Milan's website: "I went to Madrid to see Atletico play and I have information on all the players.
"Atletico are a team that have the ability to play when in control of the game but containment is a strategy that their coach uses and I expected them to play as they did.
"We know that the match in Madrid will be an important one but we have time to prepare."