Barcelona stand-in coach Jordi Roura has called for the referee to "go unnoticed" during his side's Copa del Rey clash with Real Madrid at Camp Nou on Tuesday.
The game will be officiated by Alberto Undiano Mallecano, who also took charge of the final of the competition between the two rivals in 2011, and the 45-year-old is hoping he will not ignore any tough Blancos tackling.
"The numbers [with Undiano] aren't good. We still remember that he allowed many fouls in the cup final," he told reporters.
"We hope that their decisions do not mark the match and that they go unnoticed. Every Clasico is intense, hard. But we hope it won't run out of hand and that it stays within the sporting limits."
Lionel Messi has come in for criticism from certain parts of the media after allegedly insulting Madrid assistant coach Aitor Karanka, and Roura went on to defend his charge.
"Every player can improve, but looking at his numbers this season, I think the campaign by some media against Messi is out of place."
Barcelona have conceded a number of seemingly unnecessary goals this season, and Roura was quick to assure supporters that they are working to address the issue.
"We've analysed the goals we've conceded. Sometimes the opponent just did well, other times we've made mistakes. We need to focus more."
Barcelona and Real Madrid kick off at 21:00CET on Tuesday, having recorded a 1-1 first-leg draw at the Santiago Bernabeu in the first leg.