Sierra wrestled in World Championship Wrestling (WCW), making appearances between 1994 and 1997. He is known for a feud with Jim Duggan. In WCW, Fidel Sierra regularly teamed with Ricky Santana. Originally billed as The Cuban Connection, the duo were renamed The Barrio Brothers (Ricky Barrio and Fidel Barrio) in the mid-1990's. Sierra and Santana also performed in WCW wearing masks and full-body suits as Los Especialistas (Especialista I and Especialista II). Their identities were revealed on-air on the live Main Event pre-show of Clash of the Champions XXXI, when they were unmasked by The Nasty Boys following a match.
In between his WCW appearances, Sierra also wrestled several matches for the World Wrestling Federation in 1994 and 1995. He made his first appearance on the February 5, 1994 episode of WWF Superstars, teaming with Barry Horowitz in a loss to The 1-2-3 Kid and Marty Jannetty. He then teamed with Ricky Santana in two tryout matches at WWF television tapings that June, though the pair was not signed. Sierra would make two more appearances on WWF television in 1995 as 'David Sierra', losing to Aldo Montoya on the January 30 episode of Monday Night Raw and once again teaming with Barry Horowitz to lose to Men on a Mission on the February 9 edition of WWF Wrestling Challenge.