Almagro bounced back from a lopsided first set to beat Juan Ignacio Chela 1-6, 6-2, 6-4 on Friday and reach the final.
Almagro, who won this tournament in 2008, will be bidding for his eighth ATP title, and the previous seven have come on clay - the surface in Brazil.
Almagro closed out the match by breaking fifth-seeded Chela of Argentina in the final game to take the third set.
Fourth-seeded Dolgopolov of Ukraine, a quarterfinalist in the Australian Open, reached his first ATP final with a 59-minute victory over Ricardo Mello of Brazil, 6-2, 6-1.
Agent - No Fabiano bidsChela advances to second round
