The Rojiblancos routed the Rossoneri 5-1 on aggregate and the Argentine is hoping that his troops can now carry that form into their 11 remaining Liga "cup finals"
The Rojiblancos stormed into the quarter-finals of Europe's elite cup competition by routing the Rossoneri 4-1 at the Vicente Calderon on Tuesday night to progress 5-1 on aggregate.
Simeone is well aware that Atletico have won nothing yet but feels that their midweek mauling of Milan represents another important step in his team's development into a genuine continental colossus.
"It was very important for the club, for our fans and for the players," the Argentine told reporters.
"It's very important to be amongst Europe's best. Even though it doesn't assure you of anything, it shows the side are continuing to grow and develop.
"The team have gotten stronger for the result and the job done."
Simeone is now hoping that the confidence derived from overcoming Milan will aid Atletico's Primera Division title challenge, with the Rojiblancos currently second in the standings, just three points behind city rivals Real.
"I said a while ago that all games are finals, and we now have 11 more," the former midfield ace pointed out.
"But the best way to get motivated is to forget about our rivals and look at our stadium, full of fans, and what it means to wear this shirt and see what we are achieving.
"We're a difficult side for everyone."
Simeone admitted, though, that Atletico will face a tough test this weekend against an Espanyol side that defeated them 1-0 in Catalunya earlier this season.
"They beat us well," he acknowledged. "They played a great game, with intensity.
"Aguirre prepared for the tie well, he's a smart coach. Given this game and the result, we have to be alert and attentive."
Atletico's meeting with Espanyol at the Vicente Calderon is scheduled to kick off at 21:00GMT on Saturday.