The Catalans are only ahead of Diego Simeone's side at the top of the Primera Division on goal difference and Sevilla have not lost in the league since November 2, but 19th-placed Rayo should prove more palatable opponents for Atletico.
Los Rojiblancos boast the best defence in the league, conceding just 12 times this season, while Rayo have the worst - along with bottom-side Real Betis - shipping 47 goals in just 20 games.
However, Paco Jemez's side got the better of Atletico last season, winning 2-1 in Vallecas, and Simeone does not expect any respite this year.
He told a press conference: "Tomorrow I expect that Rayo will play like they always do. They are not going to change their style against us.
"They have a very bold coach who makes them play a smooth passing game with a lot of pressing. Last year they complicated things for us in Vallecas. I imagine the game will be similar to the last few games we've been playing ."
On Sunday Atletico will play their seventh game in January, and the consecutive draws, plus narrow and hard-fought wins over Malaga, Valencia and Athletic Bilbao have raised inevitable questions about whether Simeone's squad can cope with playing so many games in the league, the Copa del Rey and the Champions League.
"Tiredness exists but you learn to deal with it," said the Argentinian coach.
"Ideally we will begin to learn to deal with it better. The team are still alive in all competitions and we have to go through this process of adaptation.
"In my first year we did well in the league and the Europa League. In the second season we were knocked out of the Europa League in February but did well in the league and the Copa del Rey. Now we are trying to keep on growing."
Simeone will be without first choice full-back Juanfran Torres, meaning academy graduate Javier Manquillo is expected to start in Vallecas, but otherwise Atleti will field a similar team to the one that drew 1-1 with Sevilla, missing the opportunity to go above Barcelona in the league table.
Rayo, meanwhile, passed up the opportunity to climb out of the relegation zone last weekend, losing 2-0 at fellow strugglers Elche.
Raul Baena was sent off early in the game, giving away the penalty which lead to the opening goal, but the midfielder's red card has been rescinded and he is free to face Atletico.
Jemez's side are three points from safety but could still exit the drop zone this weekend, provided they beat Atletico and Almeria lose to Getafe.
Goalkeeper Ruben Martinez refuses to rule out such an outcome, telling reporters: "If we show courage and get enough luck to beat Atletico, we could exit the relegation zone.
"Imagine what that would mean for our morale and confidence."