Dan Peterson, a short, white-haired, 82-year-old man who looked perfectly Italian in a puffy vest over a sharp gray suit, took his courtside seat before a recent Olimpia Milano basketball game. “Buonasera, coach!” his fans said. They wanted handshakes. They wanted selfies. They wanted to say they had met Dan Peterson.

Peterson is one of the most overlooked, influential figures in the history of the sport because he didn’t play or coach in the NBA. He’s been overseas for almost his entire career. He also happens to be from the Chicago suburbs. The reason that Peterson is a celebrity abroad but almost entirely unknown in the United States is that he moved to Italy about 45 years ago and never left.