Real Madrid coach Jose Mourinho believes Barcelona should focus on football rather than talking about the referees ahead of the second-leg Copa del Rey clash at the Camp Nou.Barcelona interim coach Jordi Roura voiced his reservations over the appointment of Alberto Undiano Mallecano as the referee for the Clasico, and the Blancos trainer feels they should concentrate on the game itself."I prefer to stay with the lessons we have received in the past from Barcelona. Lessons in sportsmanship, how to be in football. Not talking about the referees, not the surroundings," he sarcastically told reporters."And, of course, giving lessons on how to play football, they do that very well. They would be well advised if they humbly followed that line."The former Chelsea boss is looking forward to the encounter as his side look to rescue their season with a Copa triumph."These are the games we like to play and I like going into with the players. We prefer games this dimension and this difficulty."Brazilian star Kaka starred in Madrid's 2-1 victory at Deportivo La Coruna on Saturday, but Mourinho is not sure yet if the former AC Milan star will make an appearance."I do not know. Not that I would not want to say it. I have not thought of it. Normally I do not say it. This time I do not know. "