Gutierrez and Gonzalez faced a deficit in both sets, one break in the first and two breaks in the second, but managed to come back in both to book their place in the final eight in Marbella.
Leal and Belluati were serving for the set at 5-2 in the second set, but were broken three times in a row, failing to push the match to a deciding third frame.
Top two seeds Martin Di Nenno and Franco Stupaczuk, and Arturo Coello and Agustin Tapia both saw out their matches in straight sets as well as they advance in the south east of Spain.
Watch the centre-court highlights in the video below!
Matches in chronological order:
Martin Di Nenno / Franco Stupaczuk (2) vs Jose G. Diestro / 'Pincho' Fernandez
'Sanyo' Gutierrez / 'Momo' Gonzalez (4) vs Juan C. Belluati / Javi Leal
Arturo Coello / Agustin Tapia vs Javi Barahona / Javi G. Mora
