Gregorio Peralta was born in
San Juan. He later resided in the area of
Rosario, in
Santa Fe Province. On April 5, 1958, he made his professional boxing debut, knocking out a rival (
Rene Pereira) who had lost all fourteen of his bouts. Peralta's fourth-round knockout of Pereira was at the legendary
Luna Park, in
Buenos Aires. Peralta won his first five fights by knockout, then went the ten round distance for the first time on September 6 of that same year, against
Jose Angel Manzur, whom he outpointed over ten rounds in
Montevideo, Uruguay. His first fight abroad had already been held, when he beat
Marcelo Farias by a second-round knockout 35 days before, also at Montevideo. On October 22, he and Manzur had a rematch, with the two boxers drawing (tying) after ten more rounds. On March 31, 1959, Peralta suffered his first loss as a professional, a ten-round decision defeat to then reigning South American light heavyweight champion
Luis Ignacio in São Paulo, Brazil in a non-title bout. Peralta had one loss and two draws in his next three fights, but then he returned to winning, when he avenged his defeat against Ignacio by knocking him out in three rounds, August 23 in Brazil. After winning his next five fights, including four in
Uruguay, Peralta faced
Mauro Mina, in a widely expected light heavyweight bout between two
South Americans. On June 15, 1960, Peralta was knocked out by Mina in eight rounds at
Lima, Peru. Peralta then won twelve and drew one of his next thirteen bouts. Among those were a ten-round decision in a rubber match with Manzur, and a four-round
disqualification win over
Aurelio Diaz. Peralta was given his first chance at winning a belt when he fought
Jose Giorgetti, on August 4, 1962, at
Mar del Plata for the Argentine Heavyweight title. He won the national belt by outpointing Giorgetti over twelve rounds, and then won fifteen more bouts in a row, for a total of 24 victories and one draw in twenty-five bouts. ==Beats Pastrano==