Carlo Ancelotti said the "issue of age is the same for veterans as it is for youth" in expressing empathy for Sergio Ramos following his international retirement from Spain.
The veteran defender announced he was calling it a day from international football earlier this week after a hugely decorated Spain career, saying head coach Luis de la Fuente had left him no choice.
Ramos racked up 180 appearances for La Roja - making him their most-capped player - while he played a vital role as they lifted the European Championship trophy in 2008 and 2012 either side of becoming world champions in South Africa in 2010.
But the Paris Saint-Germain centre-half, who turns 37 next month, last played for Spain in March 2021 and was left out of Luis Enrique's squad for Euro 2020 and the 2022 World Cup.
Although Luis Enrique's replacement De la Fuente initially said the door was open for Ramos to potentially return to the team, the defender indicated the new head coach had changed his stance when announcing his decision to call it quits.
Real Madrid boss Ancelotti, who coached Ramos during his first spell with Los Blancos between 2013 and 2015, said he can understand the frustration.
The veteran coach also highlighted notable examples to demonstrate that age is not important when determining a player's impact.
"The issue of age is the same for veterans as it is for youth," he said. "If a player complies, he does not have to look at the passport.
"If at 17 he deserves to play, let him do it. He doesn't have to play if he doesn't deserve it or if he's not better than another, the same with a 37-year-old player.
"A coach has to evaluate what happens on the field every day, in each training [session], if the player is well and can meet, no matter the age. Through thick and thin, it never has to be something to make a decision, in my opinion.
"Sometimes, they tell me I don't use the academy and forget that I put [Gianluigi] Buffon in at the age of 17 at the beginning of my career. It was because he was very good, better than others.
"The Champions League has been won by a 39-year-old player like [Paolo] Maldini, who trained once a week and played because he was better than others, period. If you are better than others, you have to play."