"Rafa understood that I wanted to manage a club again. The players understand fully why I've left and they were very supportive on Thursday, my last day," said the former first team coach.
"I've really enjoyed working with Rafa. He's a very good coach and we had great success in the last four years, when you look at what we've achieved.
"Being the first team coach was a fantastic position to be in at such a top club. I worked exceptionally hard for years with numerous clubs to try to get to the top and he gave me that chance.
"I will always be indebted to him."