John Natividad was a world-rated karate fighter before his retirement from competition in 1975. He appeared in the Top 10 polls of such publications as Black Belt and Professional Karate. His biggest year was 1973, when he won grand championship titles at the International Championships, the Colorado State Championships, Yamashita Open, Northern California Karate Championships and first places at the Las Vegas Nationals and the Black Belt Team Championships in Washington, D.C. He also owns first-place and grand championship trophies from the '72 Western States Championships, '72 Las Vegas Nationals, '71 Four Seasons, '71 Pasadena AOpen, '72 Pacific Coast Team Invitational, '71 California State Team Championships, '71 Four Seasons Fall Team Championships, '70 International Team Championships, and the 1970 Mike Stone All-Star Team championships in California where he burst into the national spotlight by defeating the top 5 National ranked competitors, most notable were Whirlwind Fred Wren, Victor Moore from New York, and Joe Lewis. That night earned him the title of "Giant Killer". He finished second in the heavyweight division of the World Pro/Am in '70, second in middleweight at the '72 Top 10 Nationals in St. Louis and '72 Grand Nationals in Alburquerque.