Russia needs only one win in Sunday's reverse singles or the doubles match to advance to the Fed Cup semifinals. Russia is seeking its fifth Fed Cup title since 2004.
Sharapova opened the series with a 6-2, 6-1 victory over Silvia Soler-Espinosa. She had 28 unforced errors and six double faults but only dropped serve once while piling up six service breaks.
Kuznetsova ran past Carla Suarez Navarro 6-3, 6-1 in 68 minutes. She won more the half the points off Suarez Navarro's serve and had five breaks in eight receiving games.
Sharapova takes on Suarez Navarro and Kuznetsova plays Soler-Espinosa in Sunday's singles matches. If the series is tied after those, Russia will send out the doubles team of Ekaterina Makarova and Nadia Petrova against Spaniards Nuria Llagostera Vives and Arantxa Parra-Santonja to decide the series.
The Russia-Spain winner goes to the April 21-22 Fed Cup semifinals against either Belgium or Serbia.