Former World No 1 Dinara Safina was forced to abandon her quarter-final against top seed Victoria Azarenka at the Andalucia Tennis Championships yesterday because of a lower-back injury.
Azarenka of Belarus was leading 5-1 when Russian Safina retired from the event.
"I feel bad winning in this way, above all against an opponent like Dinara," Azarenka said .
Azarenka will meet Sara Errani in tomorrow's semi-finals after the Italian beat fourth seed Alexandra Dulgheru of Romania 6-2, 6-2.
The other semi pairs Svetlana Kuznetsova of Russia and Romanian qualifier Irina Begu. Kuztnetsova thumped Lara Arruabarrena 6-1, 6-2 while Begu defeated Klara Zakopalova 6-3, 6-3.