The third-seeded Almagro beat Thomaz Bellucci of Brazil 7-6 (4), 6-4 in the semifinals for his 13th straight victory. He won titles in Argentina and Brazil the last two weeks.
"I am very happy," said Almagro, who is chasing his 10th title overall. "This is the product of the hard work I have done in the past, but it's not over yet."
The top-seeded Ferrer rallied to defeat Alexandr Dolgopolov of Ukraine 5-7, 6-1, 6-1, taking advantage of seven double-faults to win his second straight match in which he dropped the opening set. Ferrer converted only six of 17 break points.
Almagro, displaying the best tennis of his career, is trying to become the first player to win three of the four events on the ATP's Latin American clay-court swing. Among those who have won two are Juan Carlos Ferrero, Tommy Robredo, Rafael Nadal, Gaston Gaudio and Gustavo Kuerten.
On the women's side of the joint ATP-WTA event, Arantxa Parra Santonja of Spain will meet Gisela Dulko of Argentina in the final. Parra Santonja defeated Johanna Larsson of Sweden 6-2, 6-0, while Dulko cruised over Anabel Medina Garrigues of Spain 6-0, 6-2.