At 36, Monreal has explained last season's injury-plagued campaign with La Real convinced him to hang up the boots.
"I can't do any more!" declared Monreal on social media. “Do I get angry with this? Nope! I listen to it, I accept it and I thank it for everything.
"A new stage begins today, but I feel good and that gives me peace of mind.
“36 years playing soccer. 16 of them as a professional. Squeezing my body to the fullest, taking it to limits that I would never have imagined being able to reach. My knee sends me a message, a message loud and clear."