sentences:  Additionally he has held multiple interim titles at lightweight and welterweight.Guerrero is trained by his father Ruben Guerrero, a former amateur champion, who introduced Robert and his five brothers to boxing as youngsters growing up in Gilroy, California.After an impressive amateur career begun at a very young age, Robert turned professional, at the age of 18, on May 22, 2001 with a four-round unanimous decision win against Alejandro Cruz.