The Portugal international defender completed his switch from Deportivo La Coruna yesterday and declared: "Everything happened very quickly, it was love at first sight.
"My agent had been in contact with the Juventus management, but there was nothing concrete until a few days ago.
"I accepted after considering every possible option and listening to my manager. In any case, the word Juventus represents a guarantee."
Juve will pay Deportivo a fee of around £7m, while the centre-back is expected to sign a three-year contract worth £1.4m per year.