Los Rojiblancos earned a 1-0 win over Espanyol on Saturday evening to remain three points behind Carlo Ancelotti's men, who had earlier defeated Malaga by the same scoreline.
Diego Costa scored the only goal of the game 10 minutes into the second half to complete a memorable week for Atletico, who reached the quarter-finals of the Champions League for the first time since 1997 in midweek with a 5-1 aggregate thrashing of Italian giants AC Milan.
Simeone said: "The players are doing something extraordinary. I am speechless because they do their best to find results. I have admiration for this group of players."
The Argentinian admitted his side did not have it all their own way against Espanyol, however.
"They had no great chances although they were able to attack," he added.
"We were not accurate in the first half and we weren't fast enough, or playing between the lines."
Defender Filipe Luis echoed his manager's sentiments and was thrilled to emerge with all three points against Espanyol.
"Espanyol have a great coach who knows how to play against us," the Brazilian said. "Playing against Espanyol has never been easy, the three points are very sweet, we are excited to continue."
After a shaky first half, Atletico began the second half well and they went ahead 10 minutes in after Diego Costa picked up David Villa's cross from the left and curled into the bottom of the net from 12 yards out for his 29th goal of the season.
Filipe Luis added of the Spanish forward: "Every time the game is complicated where there are a few chances, the team are thrilled to have him and hopefully he can continue at this level."