Ezequiel Garay has extraordinarily hit out at Valencia for sacking Marcelino three matches into the new La Liga season.
Marcelino departed on Wednesday despite leading the club to successive top-four finishes in the past two campaigns.
He also won the Copa del Rey with the club last term - beating Barcelona in the final - but following a reported falling out with owner Peter Lim he has been replaced by Albert Celades.
Garay, who started all three La Liga games this season under Marcelino, made his feelings clear with an explosive social media post.
"After many years with you (not just at Valencia) I know perfectly well who you are, both professionally and personally," he wrote on Instagram.
"But I'm not just thinking about that, you've shown that to everybody. Because actions speak louder than words and you have had a clean, transparent and healthy journey. You are walking out the front door sir.
"Who ever made this decision did NOT just walk over you, they have dragged the whole team and support down with them, something I will say loud and clear: IT'S NOT FAIR."
Dani Parejo, Valencia's captain, also was unimpressed with the club's call to replace Marcelino, and credited the coach with making him and the club better.
"Sir, I wish you the best.," Parejo wrote on Twitter alongside a photograph of him embracing the coach.
"I am sure you'll do well wherever you go and work. Thanks for making this club bigger and me a better footballer."