MADRID, Spain -- Real Madrid and former Spain midfielder Ruben de la Red has retired because of a heart problem.

De la Red collapsed during a Copa del Rey match in 2008 and has not played in a game since. The 25-year-old will remain with Real Madrid as an assistant to boss Jose Mourinho.

"I may have a problem in my heart, but it still beats for Madridismo," De La Red said. "Jose Mourinho was very aware of my situation since day one and he was very clear when he spoke to me.

"He told me he counted on me if I was able to play, but if that wasn't the case, he said he would be delighted to have me in his staff."