Coello and Tapia have now won ten matches in a row to start the 2023 season, although they did concede a set for the first time this campaign.
27th-ranked Martinez and Mendez took the opening frame, forcing Coello and Tapia to mount a comeback to claim their spot in the quarter-finals.
Number ones of the world Juan Lebron and Alejandro Galan returned to action as well after missing the La Rioja Open, and looked as good as ever in their Chilean debut.
They took on teenagers David Gala and Daniel Santigosa, both of which had never been in the round of 16 before, while Franco Stupaczuk and Martin Di Nenno faced Miguel Yanguas and Leandro Augsburger.
Watch all of the centre court highlights in the video below!
Matches in chronological order:
Juan Lebron (ESP)/Alejandro Galan (ESP) (1) vs Daniel Santigosa (ESP)/David Gala (ESP)
Martin Di Nenno (ARG)/Franco Stupaczuk (ARG) (4) vs Miguel Yanguas (ESP)/Leandro Augsburger (ARG)
Arturo Coello (ESP)/Agustin Tapia (ARG) (2) vs Javier Martinez (ESP)/Rafael Mendez (ESP)