Atletico and Arsenal played out a 1-1 draw in the first-leg of their Champions League semifinal, with both teams converting penalties.
Simeone said afterwards: "The first half was evenly matched – maybe they had more possession, but they didn't create many chances.
"They have a very strong squad: when the substitutes came on, they were better than the starters. Even so, we were better than them in the second half.
"They eased off a bit, and we got our organisation together. We were better at the back and created chances through Griezmann and Lookman."
On the home support, the Argentine added: "Today was incredible. Rarely have we seen such enthusiasm as we had at the start of the match. They won’t all be there for the second leg, but their hearts and souls will be."