Atlético Madrid goalkeeper Jan Oblak has appealed to Real Madrid to leave "the referees in peace" ahead of Saturday's derby.

Real Madrid have come under scrutiny for sending an open letter to the Royal Spanish Football Federation (RFEF) accusing officials of "manipulation and adulteration."

The letter was sent after Real Madrid's 1-0 defeat at Espanyol last weekend.

"The best way is to leave referees in peace and that way they can do their job at their best possible level," Oblak told ESPN. "That is the most important thing for football, not just for the teams, for everyone. It's not the referees who will decide the game."

Atlético defender José María Giménez echoed Oblak's comments.

"As players, we focus on our jobs," the Uruguay centre-back told ESPN. "I hope that what has happened doesn't go beyond a statement and that no one feels affected or pressured. That we have a clean game, that there are no issues in the post-game and that the grey episodes are interpreted in the best possible way."

Veteran Atlético defender César Azpilicueta, meanwhile, brushed aside Real Madrid's concerns about refereeing.

"When you step on the pitch you believe that everybody does their best that we can to get our job done," the former Chelsea captain told ESPN. "I don't think twice about it."

Atlético, who progressed to the Round of 16 of the Champions League, are one point adrift of Carlo Ancelotti's LaLiga leaders heading into this weekend's derby at the Bernabéu.

Diego Simeone's team beat Getafe 5-0 on Tuesday to progress to the Copa del Rey semifinals.

"We know we arrive in good shape," Azpilicueta said. "But we know how football is, and it can change very quickly. We have to work to maintain that momentum and get the result. Confidence comes with the results and when you win that helps everyone individually and collectively to be pushing every week even harder."

While Azpilicueta expressed the need for his team to not get too far ahead of themselves, he is cautiously optimistic about Atlético's chances of reaching the final.

"Until now, we are still in every competition, fighting," Azpilicueta said. "It's in our hands. Although in February you don't win any titles, you can lose them. Our job now is to be in contention for the last couple of weeks when everything can be decided when you get closer to the end. We believe we have the group and the team to make it happen. We need to have the same confidence and togetherness to get it done."

Limiting Real Madrid's attack on Saturday will take a team effort.

"The only way to stop them is to work as a team, defensively and in attack," Atlético defender Nahuel Molina told ESPN. "We know they have great players and not to concede a goal will be key."

Giménez, meanwhile, knows they will have their work cut out to stop a Real Madrid attack led by LaLiga's leading scorer Kylian Mbappé.

"Mbappé didn't start [life at Real Madrid] the way he wanted but he is already showing what type of player he is," he said. "They [Real Madrid] have an attacking line that competes very well, that is fast, have a lot of vision of play. "We have to play a perfect game not to concede a goal."

Oblak expressed a similar sentiment.

"The key is simple, be good in defence, be good in attack," he said. "It's not always easy to do. The important thing is to keep a cold head, be aware of their danger."