"We are disappointed because we will miss Sami," said the Reds boss.
"He is so important that we talked about him becoming a member of the coaching staff in the future, but he thinks he can play more and wants to be involved in the first team.
"The fact that we were talking to him about becoming a coach shows how much we think of him - he is a perfect professional.
"We were talking to him about an extension to his contract and the guarantee of becoming a member of the coaching staff. That shows we were really pleased with him and how good he is as a professional."