NEW YORK, NY, USA - Defending US Open doubles champions and top seeds Liezel Huber and Lisa Raymond suffered a shock third round defeat at the hands of Hsieh Su-Wei and Anabel Medina Garrigues on Sunday.
Despite winning five more points than their opponents, Huber and Raymond were punished for their profligate return game, slipping to a 64 26 64 defeat after battling it out for over two hours in the midday sun.
The US Open is just Hsieh and Medina Garrigues' second tournament together, but they looked anything but a novice pairing, playing an error-free match and capitalizing on any chances that came their way. After splitting the first two sets, they fended off five break points in the decider, before claiming the decisive break themselves to secure a famous victory.
Meeting them next will be Chuang Chia-Jung and Zhang Shuai, who defeated fellow unseeded pairing Angelique Kerber and Tamira Paszek, 67(7) 75 60.
Elsewhere, there was better news for the other leading seeds as both Sara Errani and Roberta Vinci and the in-form Andrea Hlavackova and Lucie Hradecka advanced into the quarterfinals.
Hlavackova and Hradecka have had a summer to remember - winning in Cincinnati and finishing runners-up at Wimbledon and the Olympics - and defeated Natalie Grandin and Vladimira Uhlirova, 63 63, for their 24th win in the last 28 matches.
No.2 seeds Errani and Vinci were made to work somewhat harder, edging out their opponents Bethanie Mattek-Sands and Sania Mirza, 64 67(7) 63.
The remaining third round matches will take place on Monday, with former champions Serena and Venus Williams and Vania King and Yaroslava Shvedova among the teams hoping to progress.