Russian Svetlana Kuznetsova has become the latest seed to fall at the Auckland tennis classic, losing to Austrian qualifier Tamira Paszek in straight sets.
No.4 seed Kuznetsova, the world No.25 and two-time grand slam winner, lost 6-2 6-3 on Wednesday in the second round to an opponent ranked 172.
She is the fifth seeded player to exit the tournament, the others including the top two drawcards - American Venus Williams and Serbian second seed Ana Ivanovic - in the opening round.
It was Paszek's second win over a major winner this week, after downing former French Open champion Francesca Schiavone of Italy on Tuesday in a marathon three-setter.
The 25-year-old Paszek, a semi-finalist in Auckland in 2008, produced some excellent winners with her ground strokes, while Kuznetsova struggled at times to find her rhythm.
In the quarter-finals, Paszek will meet Belgian qualifier Kirsten Flipkens or unseeded American Irina Falconi.
American fifth seed Sloane Stephens made it through to the last eight by beating German Carina Witthoeft 3-6 6-1 6-3.
Stephens will next face Latvian wildcard Jelena Ostapenko or British qualifier Naomi Broady.
Ivanovic, meanwhile, has withdrawn from the doubles event because of headaches and dizziness.
Ivanovic had been due to take the court with Flipkens on Wednesday afternoon in a quarter-final against Belgian combination Elise Mertens and An-Sophie Mestach.
But she decided with Flipkens and with her coaching team to pull out to recover and focus on getting to Sydney fit and healthy.
The 2014 Auckland singles champion was upset on Tuesday night in the opening round, the world No.16 falling to British qualifier Naomi Broady 7-5 6-4.
Ivanovic said she intended returning to New Zealand.
"I love being in Auckland for the ASB Classic and I really want to come back in 2017 and give the title another go," she said.
"I really feel at home here in Auckland. I promise to all my fans that I will be back soon."
