Sania Mirza and her American partner Bethanie Mattek bowed out of the WTA East West Bank Classic tournament after retiring midway through their semifinal match.

Second seeds Sania and Mattek were trailing 2-6, 1-2 when they pulled out of their match against the Czech pair of Eva Hrdinova and Vladimira Uhlirova in the tier II $600,000 hard court event.

The Indo-American pair had to pull out after Mattek complained of a low back injury.

Meanwhile, Hrdinova and Uhlirova will take on top seeds Chan Yung-Jan and Chuang Chia-Jung, who beat number four seeds Lisa Raymond and Samantha Stosur in a match tie-break, 7-6 (3), 3-6, 10-7.