5'7, I believe. And had some condition where he scarcely hit puberty, had a hormone deficiency or something..
Though there is increasing height bias in football. Possibly just in our country though, where we have hordes of coaches who promote youngsters based on size over technical ability. I doubt it's the same in Spain or Italy, amongst others.
Just on Barca alone, there are players shorter than he. It's a matter of position - if you're 5'5'', you can't be a goalkeeper, but a midfielder/wingback/attacker you can if you possess the talent.