Knezic grew up in Cudahy, Wisconsin where in 1967 he began playing youth soccer with the Milwaukee Serbians.
He attended the University of Wisconsin–Milwaukee where he was a 1979 Honorable Mention (third team) All American soccer player.
[3] In 1985, he moved to the Tulsa Tornados, but the team and league collapsed six games into the season.
[4] In the fall of 1985, he signed with the Milwaukee Wave of the American Indoor Soccer Association.
Knezic suffered from back problems during the 1986–1987 season and when not playing, served as the team's assistant coach and general manager for player personnel.