Mazzei, who is survived by his wife, Maria Elena, and children Marjorie and Julio Jr., had suffered from Alzheimer's Disease for the past nine years.
Mazzei, who earned the nickname "Professor" as the head of the physical education department at the University of Sao Paulo, received a master's degree from Michigan State. He first worked with Pele as his fitness trainer and advised the Brazilian great when he signed with the Cosmos in 1975.
He was named Cosmos technical director in 1979 after the firing of Eddie Firmani. In 1982, Mazzei replaced legendary German coach Hennes Weisweiler and led the Cosmos to their fifth and final NASL title.
After the end of the NASL, Mazzei remained active in American soccer.
For New York soccer journalist Michael Lewis' interviews with those who knew Professor Mazzei well, click here.