Sanchez-Vicario played in her record-tying 57th Fed Cup tie, equaling the mark held by Britain's Virginia Wade. The all-time leader in Fed Cup wins notched her 72nd in the international competition with a 6-3, 7-6 (7-5) victory over Barbara Schett.
Earlier, Martinez gave Spain the first point with a 6-0, 7-5 triumph over Patricia Wartusch in the opening match at the Palacio de Congresos de Pampalomas.
Sanchez-Vicario and Martinez are trying to lead Spain to its sixth Fed Cup title. They first claimed the crown in 1991 and are trying to move Spain into the final for the 10th time in 14 years.
As far as Sanchez-Vicario is concerned, it never gets old.
"I think that you always remember your first victory," she said. "Your dream comes true to win the Fed Cup. Conchita and I were very young when we first played and we are happy to have a chance maybe to win again, more than 10 years later. We are better players with more experience and it would mean a lot to win the Fed Cup for myself, for the crowd and for my country."
Trying to reach its first Fed Cup final, Austria will try to rally Thursday in the reverse singles and doubles match between Schett and Wartusch and Spain's Virginia Ruano Pascual and Magui Serna.
Austria ousted the United States in the quarterfinals in April.
In the second semifinal, Italy split its singles matches with favored Slovakia.
Playing in her first Fed Cup match, the 41st-ranked Schiavone showed no signs of nerves, breaking serve in the opening game. After winning the first set in a tiebreaker, the Italian broke Hantuchova twice in the second set, giving Italy the point.
"I think Francesca played really well today -- she didn't miss a ball," said Hantuchova, who lost to Schiavone in Paris in February. "The surface suited her. It was slow and she could get to every ball. I made too many errors today."
Janette Husarova picked up her teammate with a 6-4, 6-3 victory in just 69 minutes over world No. 16 Silvia Farina Elia.
On Thursday, Hantuchova plays Farina Elia and Husarova faces Schiavone. Hantuchova and Husarova will team up in doubles against Farina Elia and Roberta Vinci.
"The tie is still wide open," Italian captain Corrado Barrazzutti. said. "No one expected both No. 1 players to lose today and that means that the tennis is very equal on the court. It will depend on how the players feel tomorrow."