It is the first time for both Gala and Santigosa, who won the qualifying rounds ahead of the tournament, that they make the round of 16.
At 17 and 18 years old respectively, they now face three-time reigning number ones Juan Lebron and Alejandro Galan on Thursday.
Earlier at centre court of the Universidad Católica, Fede Chingotto and Javi Garrido got back to winning ways, while La Rioja semi-finalists Miguel Lamperti and Juan Cruz Belluati faced an early exit.
Watch all of the highlights in the video below!
Matches in chronological order:
Federico Chingotto (ARG)/Javi Garrido (ESP) (7) vs Edu Alonso (ESP)/Juanlu Esbri (ESP)
Lucas Campagnolo (BRA)/Maxi Sanchez (ARG) (8) vs Juan C. Belluati (ARG)/Miguel Lamperti (ARG)
David Gala (ESP)/Daniel Santigosa (ESP) vs Javi Valdes (CHL)/Facundo Dominguez (ARG) (W.C.)