He was offered (and declined) a spot on the Spain national team in 2004, preferring to play for Argentina.
Xavi. Iniesta. Fabregas. Messi? These stars all could have been Spain's present midfield if only Messi had accepted his adopted nation's invitation to join their national team in 2004. Instead, his intense loyalty to his home country drove Messi to play for Argentina. The implications of this move are almost too numerous to fathom, but at the very least we'd be talking about this generation of Spain as possibly the greatest national team, ever.