Sania Mirza and Liezel Huber were stretched by Lino Dominguez and Medina Garrigues before advancing to the quarter-finals in the Amelia Island tennis tournament.
The Indo-South African pair beat the Spanish duo 7-6(7), 6-7(6), 6-3.
In an evenly balanced contest on Wednesday, Sania and Huber won the first set over the tie-breaker at 9-7, but the Spanish girls, despite trailing, mounted pressure and forced another tie-breaker in the second set, which they won 8-6.
But just when Sania-Huber started looking out of sorts, Lino-Medina ran out of steam. They were broken twice and Indo-South African pair comfortably sealed the decider at 6-3.
In the quarterfinals, they meet Nicole Pratt and Bryanne Stewart of Australia.
On Tuesday, Sania was knocked out 3-6, 4-6 by American Lisa Raymond in the first round of the singles.
