Second-half goals from Diego Godin and Raul Garcia helped Atletico to a 2-0 win in the Copa del Rey second leg, sending them into the quarter-finals 3-1 on aggregate.
The win came just three days after Atletico drew 0-0 at home to Barcelona in a top-of-the-table La Liga clash.
Simeone said his team proved their critics, who felt tiredness would be an issue, wrong with their display.
"After a big game, when people were doubtful about the answer of the players, they were amazing again," he said.
"There is a big work of the physiotherapists, doctors and basically big work of the players. You can't play in this intensive rhythm without ambition.
"You can play better or worse but there is a team who respond in key moments."
Simeone said the way Atletico worked as a team was crucial as nine of the starting 11 which took on Barcelona were on from the outset again.
"The tiredness of the competition is starting to appear but we have to play, we have to rest, we have to eat good and basically we have to read properly the games," he said.
"How we have to run less and how we have to work in a team to run less. I think it was a good example tonight when we had to defence. We shared the efforts and we did correctly."
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.