Meanwhile, Simeone has also led his side into the semi-finals of the Champions League, where they will face Premier League outfit Chelsea.
"It makes a difference. The head must be very strong to fight the giants of European football," Diego, who is on loan from Wolfsburg, told reporters at a press conference.
"Everything else is earned by Atletico Madrid. A winning team has been built by Simeone, psychologically strong and ready to win, at all costs."
Simeone took charge of Atletico in 2011.