BASTAD, Sweden - World No.9 Caroline Wozniacki fought her way into the semifinals of the Collector Swedish Open Women on Thursday, dispatching Maria Kirilenko, 75 76(4). Dominika Cibulkova wasn't so lucky, however.

Wozniacki, the top seed, had beaten Kirilenko handily in their two prior meetings, 62 60 at Indian Wells last year and 60 64 at Wimbledon two weeks ago. But this time the Russian, unseeded, was a very stern challenge, pushing the Danish teen to the limit for two hours and 19 minutes. She even held set point at 5-4 in the first set and served for the second set, also at 5-4.

Next up for Wozniacki will be No.3 seed Flavia Pennetta, who beat Alla Kudryavtseva in the last match of the day, 64 62. Although Pennetta has spent much of the last few years in the Top 20 and Wozniacki is now in the Top 10, surprisingly the two have never played on the Sony Ericsson WTA Tour - that will all change in the next round.

Second seed Cibulkova had the fight of her life against Gisela Dulko, who had upset No.5 seed Sorana Cirstea a day earlier in another nail-biter, saving four match points and winning in a third set tie-break. Against Cibulkova she pulled off the unthinkable again, this time saving two match points down 6-4 in another third set tie-break to win, 67(5) 63 76(6). It lasted three hours and 19 minutes.

Dulko next faces another upset artist, as María José Martínez Sánchez continued to wreak havoc on her quarter of the draw. Having upset No.4 seed Kaia Kanepi in the first round, Martínez Sánchez picked off the other seed in her section in the quarters, beating No.7 seed Carla Suárez Navarro, 46 63 60.

World No.46 Dulko and world No.66 Martínez Sánchez have met just once before, with Martínez Sánchez prevailing in the Bogotá final earlier this year.