The 22-year-old Francisco defeated No.5 seed Albert Ramos-Vinolas, from Spain, 7-6 (7-5) 3-6 6-2 to book his place in an ATP final for the first time.
Having qualified for the main draw, he will tackle No.1 seed, compatriot and world No.9 Diego Schwartzman in the final after he saw off Miomir Kecmanovic of Serbia 6-0 6-4.
Last weekend, 19-year-old Juan Manuel Cerundolo, ranked a lowly No.181 in the world, claimed the Cordoba title on his main draw debut by beating Ramos-Vinolas in the final.
No brothers have ever won an ATP title in back-to-back weeks.
Schwartzman, 28, will play his 11th final on Monday (AEDT,) where he will be looking for a fourth title.