Kuznetsova, who also won the decisive match in the 2007 cup, outlasted the Spanish player 5-7, 6-3, 6-1. The win gave Russia a winning 3-0 advantage in the best-of-five competition.
Earlier in the event, Kuznetsova downed Carla Suarez Navarro 6-3, 6-1 and teammate Vera Zvonareva topped Medina Garrigues 6-3, 6-4.
Russian teams have won four of the last five Fed Cup titles.
The United States has the most Fed Cup victories with 17, followed by Australia (7), Spain (5), Czech Republic, which formerly played as Czechoslovkia (5) and Russia (4).