On March 12, he rematched Francisco Gomez, having his hand raised as winner by an eight-round unanimous decision at Santiago de los Caballeros; this was his first professional bout to take place at his hometown.
On August 18, 1975, Guzman somewhat surprisingly lost his condition as an undefeated boxer when matched against Puerto Rican prospect Luis Rosario, 3–0–1 coming in, at Santo Domingo.
WBA world Junior Flyweight champion Jaime Rios of Panama was 18–1–1 when he came to the Dominican Republic to defend his title against local Guzman during June 1976.
Three months later, on October 10, 1976, he travelled to Yamanashi, Japan, to meet 8–0 challenger, Yoko Gushiken, who stopped Guzman in seven rounds to take the world title away.
Guzman took off more than one year away from boxing before returning on November 19, 1979, beating Santos Nunez, a fighter with a negative, 1–6 record, by a ten-round unanimous decision at San Juan, Puerto Rico.
This was followed by another defeat, this time at the hands of future Lupe Pintor world Bantamweight title challenger Jovito Rengifo at Caracas, Venezuela, by an eighth-round knockout, on February 1, 1980.
Then, Guzman fought popular Mexican fighter, future North American Boxing Federation Bantamweight champion Candido Tellez, on September 4, 1980 at Los Angeles, losing by knockout in round one.
He lost both by first-round knockouts, to future world Flyweight champion Eleoncio Mercedes and to Chilean national hero Martin Vargas.