Spurs will face Sunderland at White Hart Lane on Saturday.
“Players like Roy Keane are essential in any team,” said Ramos.
“I loved him as a player.
“He had such personality and energy which he brought to the group and sadly those players are disappearing little by little.
“You can never say there won’t be a player like him again, but it’s just very difficult to find one with such a strong character and personality.
“I don’t know why it’s the case that there are no longer players like him, it’s something a footballer carries inside himself. It’s not something you can teach, it’s something you have naturally.”