Jack Zivic was one of five Zivic brothers who fought professionally – Joe, Jack, Fritzie, Eddie, and Pete. Jack and Pete worked in steel mills around Pittsburgh when they were chosen to represent the US at the 1920 Antwerp Olympics. The best of the brothers was Fritzie who was World Professional Welterweight Champion from October 1940-July 1941. Jack Zivic turned professional in 1921 and fought through 1930, finishing with a professional record of 40 wins (12 by KO), 28 losses, and 4 draws. He never fought for a major title.