The coach said he is well aware of the pressure being put on his side from their title rivals and fully expected the tough examination from Valencia on Sunday
The narrow away win, secured through Raul Garcia's first-half header, puts Atleti six points ahead of rivals Real Madrid having played a game more.
But with a clash against reigning champions Barcelona to come at Camp Nou on the final day of the season, Simeone is aware that just one slip could cost his side their dream.
"We have two big rivals behind us and we simply cannot afford to lose," he told Marca after the win on Sunday.
"This was an important win. We showed a great attitude and we fought nobly to get the three points.
"Valencia were very intense but I imagined they would be. I knew we were going to have a very tough first 30 minutes and every game at this stage of the season is complicated and requires a lot of effort."
Atletico will now need to swiftly turn their attentions to the continent as they travel to London to face Jose Mourinho's Chelsea in the second leg of their Champions League semi-final on Wednesday.
With the tie hanging in the balance after a goalless first game at Vicente Calderon, Simeone is well aware of the threat posed by the Blues, who secured a 2-0 win at Premier League leaders Liverpool on Sunday.
He continued: "Starting on Monday we will be focusing on the Champions League.
"Chelsea have a great team. They rotated half their team today and still won against Liverpool. We know they will create many problems for us."
Atletico, who have only lost three of their 35 Liga matches so far, face Levante and Malaga in their final matches before the season-ending finale against Barca and know that two victories in those games will wrap up the title before the trip to Catalunya.