Real Madrid great Hugo Sanchez says Barcelona have blundered allowing Luis Suarez to leave for Atletico Madrid.

He points in particular to the Uruguayan's friendship with Lionel Messi as a key reason to keep hold of him.

"They made a mistake letting him go, if they want him to be smiling in training, they need to give him a shell to protect him," Sanchez told Radio MARCA.

"Messi feels comfortable with people who understand and accompany him, if you take Suarez away you're going to affect Messi as well as Suarez.

"If you have Suarez as your right-hand man and no left-hand man, you can't let him go."