He is notable for his time in the World Wrestling Federation (today known as WWE) where he was also known as Conquistador #1 or Conquistador Uno when he teamed with fellow Puerto Rican José Estrada Sr. Rivera made his wrestling debut in April 1973 working for promoter Arturo Mendoza in the west of Puerto Rico.
[2] Untelevised victories over fellow preliminary wrestlers Rene Goulet, Butcher Vachon, Bob Bradley followed, with Rivera eventually ending 1983 in a winning streak.
[2] Rivera started 1984 continuing his winning streak throughout January of that year with televised victories over fellow preliminary wrestlers Tony Colón, Frankie Williams, and Israel Matia, and an untelevised victory over John Callahan but was eventually defeated by another preliminary wrestler, Tiger Chung Lee.
[2] Starting with an untelevised $20.000 battle royal won by André the Giant on January 21, Rivera was once again unable to move up the card and found himself on the losing end of many matches, losing to more-established stars such as S. D. Jones, Mr. Fuji, and Tony Garea, although Rivera was victorious in matches against less-established wrestlers such as Charlie Fulton and Fred Marzino.
[2] However, Rivera and Estrada surprisingly scored a victory (albeit untelevised) over the Rougeau Brothers on January 10, which became one of the team's highlights.
[4] On November 20, Rivera teamed with Chris Hawn to face his old rival and recently turned heel Paul Roma and Hercules Hernandez, known as Power and Glory.
Rivera worked as the Black Demon in 1991, his last match was a lost to the British Bulldog on May 29 on Wrestling Challenge which aired June 30.
[5] During this time, Rivera also challenged champion Tom Zenk for the WCW World Television Title, but was unsuccessful.
On March 19, 1994, Rivera had what was considered at the time, his last match, facing and defeating local wrestler El Exotico.
In 2006, after a 12-year hiatus from wrestling, Rivera returned on January 8, where he was defeated by local wrestler Glamour Boy Shane.
On January 25, 2014, Rivera surprisingly reappeared in the APW "Wrestle-Reunion 3" at a Royal Rumble match won by local wrestler Shayne Hawke.
[6] Rivera appears in Brad Balukjian's book The Six Pack: On the Open Road in Search of Wrestlemania released in 2024.