Diestro and Fernandez made their first-ever semi-final last week in Chile and will now dispute their third quarter-final of the season, both players in the best form of their respective careers.
Elsewhere, Argentinian teenagers Valentino Libaak and Leandro Augsburger managed to beat Gonzalo Rubio and Javi Ruiz, keeping their last-ever tournament together going into the quarter-finals.
Watch all of the highlights in the video below!
Matches in chronological order:
Alejandro Ruiz (ESP)/'Momo' Gonzalez (ESP) (4) vs Edu Alonso (ESP)/Juanlu Esbri (ESP)
'Lucho' Capra (ARG)/Agustin Gutierrez (ARG) (6) vs Jose G. Diestro (ESP)/'Pincho' Fernandez (ESP)
Miguel Yanguas (ESP)/Alejandro Arroyo (ESP) (8) vs Javi Barahona (ESP)/Javi Garcia Mora (ESP)
Fede Chingotto (ARG)/Javi Garrido (ESP) (5) vs Enrique Goenaga (ESP)/Jairo Bautista (ESP)
Gonzalo Rubio (ESP)/Javi Ruiz (ESP) (7) vs Valentino Libaak (ARG)/Leandro Augsburger (ARG)