Former Barcelona star Xavi lauded "natural" leader Iker Casillas after the goalkeeper's departure from Real Madrid.
Casillas ended a 25-year stay with the La Liga giants as his move to Primeira Liga outfit Porto was confirmed.
The 162-time Spain international and Xavi shared plenty of battles, as well as successes with the national team.
"I have to publicly recognise that I appreciate Iker a lot, and I sincerely think that we have a strong friendship," Xavi wrote in Marca.
"There's a lot of years together, we had passed by a lot of moments, good and bad ones, and these are the ones which stick people together. And he's a very lovable guy.
"He has been always a joker, joyful, sincerely and really competitive guy."
Xavi added: "He's affectionate and plenty of energy. He cheers you up, he jokes on you, but always being respectful. He's always being logical. He's very practical, he doesn't turn around stuff for too long."
World Cup winners together in 2010, Xavi - now at Al-Sadd in Qatar - said Casillas had helped calm the tensions between fierce rivals Real and Barca.
"For example, when the Madrid-Barcelona issue arises, and we saw it could go worse, he called me and told me, 'Pelopo - he always called me that - man, we have to fix it. We'd suffered a lot to be where we are, just to ruin it all because of this'.
"I think that if Iker hadn't mediated in the moment he did, I really don't know how the stuff would end. He's someone who participates, who contributes to the group. His leadership isn't a forced one, it's natural."