Mayor was raised and grew up in Caibarién, another municipality of Villa Clara, where he started to play baseball at the school at age 12. Originally, he began playing at first base but was quickly turned into a pitcher by the school's coach [REF].
In 1937, he led the circuit with a 1.13 earned run average and also pitched in an exhibition game against the New York Giants when they visited Cuba during their spring training [REF].