When Oscar started his career in 1964, he met tough opponents like Tom McNeely and Dick Wipperman. In his first bout in 1965, he was overmatched and defeated by veteran contender Zora Folley. Oscar left New York and returned to Argentina. He defeated Gregorio Paralta and American import, Billy Daniels. When he returned to New York in 1966, he out pointed equally rugged George Chuvalo.
Oscar was then matched with 1964 Olympic gold Medal winner, Joe Frezier. The fight was classic. Oscar had Joe down twice but Grazier came back to win a close decision. In 1867, Oscar was entered in the eight-man tourney to determine the defrocked Muhammad Ali’s successor. Oscar traveled to Germany and trounced southpaw Karl Mildenberger. In his next match he was floored twice and soundly beaten by the eventual tourney winner, Jimmy Ellis. Oscar regrouped in 1968 beating Folley in a rematch and also the respected, Leotis Martin. He was matched again with Joe Frazier for the New York version of the crown. Oscar fell behind early but he came back strong only to drop the verdict.
Bonavena would remain a mainstay in the talent rich rankings ’til the untimely end of his career.
Two years after his loss to Frazier, Oscar would face the come backing Muhammad Ali.It would be one of the most grueling fights of Ali’s career. The “Greatest” came out on tap, stopping a dead game but exhausted Oscar in round 15. In 1971, he won by disqualification over Al “Blue” Lewis. In 1972, he met former champion, Floyd Patterson. Oscar lost a very debatable decision. Two years later Ron Lyle defeated him.This loss pretty much pushed Oscar out of the title picture. Bonavena was still a rated fighter when on May 22,1976; he was shot and killed at a brothel in Las Vegas. The hard partying “Bad Boy” has finally met his match.