Initially Guerrero worked lower card matches, in the first-to-third match on the show with some success. On September 11, 1998 he defeated Mr. Águila in his first ever "Lucha de Apuestas" match, forcing his opponent to unmask and reveal his real name as part of the CMLL 65th Anniversary Show. Mr. Águila already worked for the World Wrestling Federation without his mask, so it was not seen as a surprise that he lost to Guerrero. In 1999 Último Guerrero teamed up with veteran Blue Panther to win the "Gran Alternativa" ("Grea Alternative") tournament, a tournament where a young wrestler teams with a veteran. Winning the "Gran Alternativa" tournament is often a sign that the promotion has plans to move a wrestler up the rankings. Shortly after winning the tournament, Guerrero won a match that made him the number one contender for Great Sasuke's NWA World Middleweight Championship. Último Guerrero did not win the match but the fact that he worked a featured match in CMLL's main arena, Arena México, showed that the company had plans for him.