The No. 1 and No. 2 seeds are out in Auckland's ASB Bank Classic.
No. 1 seed Sabine Lisicki was behind unseeded Angelique Kerber 6-4, 4-3 in the quarterfinal round when she withdrew from the tournament. The 22-year-old retired due to a back injury that seemed to be causing her physical discomfort throughout the entire match.
Lisicki was coming off a second-round match in which she committed 66 unforced errors and went three sets against Mona Barthel of Germany. Lisicki won the match, 7-6, 3-6, 6-3.
Kerber also upset No. 5 seed Julia Goerges in the second round, 6-2, 6-3. According to the New Zealand Herald, Goerges was "affected by an illness."
No. 2 seed Peng Shuai was also ousted from the tournament. Lucie Hradecka of the Czech Republic defeated Shuai, 6-4, 6-3.
Sixth-seeded Roberta Vinci was also knocked from the tournament in straight sets. Vinci lost 6-3, 6-4 to Elena Vesnina of Russia.
No. 3 seed Svetlana Kuznetsova remains in the tournament after a 6-1, 6-1 defeat of American Christina McHale.