The third-seeded Americans split the first two sets with Jelena Jankovic and Andrea Petkovic, and then the two teams went at it for 23 more minutes, just two minutes shorter than the length of the entire second set.
The match tie-break featured match points for Jankovic and Petkovic at 9-8, 10-9, 11-10 and 13-12. And Kops-Jones and Spears had match points at 12-11 and 14-13 before finally converting at 15-14 for the 64 16 1614 triumph.
Kops-Jones and Spears had played 76 match tie-breaks as a duo before Thursday, 62 of them at the WTA level, and had never gone beyond 14-12 in one. Interestingly enough, that happened twice and they won both - at Rome in 2011 and at Carlsbad in 2012.
Thursday's other quarterfinal also was settled in a match tie-break, not a surprise considering that only two doubles matches haven't gone the distance this week. In this case, Chan Hao-Ching and Chan Yung-Jan were 63 46 108 winners over Sorana Cirstea and Maria Kirilenko.
In the last remaining first round match, Marina Erakovic and Arantxa Parra Santonja advanced when No.1 seeds Hsieh Su-Wei and Peng Shuai were forced to retire down 5-4 but on serve in the first set because of an abdominal strain suffered by Peng.
"It's our first time playing together," Parra Santonja said. "We have to get to know each other a little bit more, but I think we were playing well today before the injury, and I think we will keep improving."