I'm confused

I thought Alex was his name and Sandro his last name.
It's different in the case of the Dutch, as far as I know van is part of their last name, just like some Spanish last names have de, del or de la as part of theirs. You know, del Bosque, de la Red, etc
I think in that case would be OK to call him Sandro, we don't need to call every player by their full name, when you say Pogba or Dybala you know who their are without having to add Paul or Paulo to it