Xavi, speaking on Romario's YouTube channel, was asked if there will be a 'new' Messi to emerge in the coming years.
He said: "I hope I'm wrong because I'd like them to improve Messi, but I don't think it's going to happen. I lived with Leo every day for 15 years, and he was the best at everything: technique, physicality, understanding the game, heading, his weaker foot, his mentality... he's a competitive animal. Unbeatable.
"When you gave him the ball, he improved everything and made you better. I was a passer. He was from another planet—well, he is, because he's going to play in a World Cup. Besides, he's a humble, hardworking, disciplined, perfectionist person.
"I saw him when I was 16. He's a phenomenon, from another planet, and also a good person. A good guy.
"I tried to get him to come back to Barcelona, but in the end, the president said no."