Melbourne: Petra Kvitova moved into the semifinals at the Australian Open for the first time and kept alive her chances of claiming the No. 1 ranking with a 6-4, 6-4 win over Sara Errani on Wednesday.
The second-seeded Kvitova wasn't at her best, finishing with 44 unforced errors, and had to come from a break down in the second set before sealing victory.
Errani was playing in her first Grand Slam quarterfinal. She is now 0-25 against top 10 players.
"I expected it to be very tough," Kvitova said. "She played very well today and the days before."
Kvitova is the first Czech woman to reach the semifinals at Melbourne Park since 1991 finalist Jana Novotna. Another Czech-born great, Martina Navratilova, has been lending her support to the 21-year-old.
"I get some emails from her and it's really nice to know a big legend is supporting you," Kvitova said. "I really like her."
Kvitova will face the winner of a later quarterfinal match between Maria Sharapova and Ekaterina Makarova, who knocked out Serena Williams in the previous round.
Wimbledon champion Kvitova is vying with Sharapova and Victoria Azarenka for the top ranking, which Caroline Wozniacki will vacate on Monday after her quarterfinal loss to Kim Clijsters.
The men's semifinal lineup will also be completed Wednesday.
Defending champion Novak Djokovic is up against fifth-seeded David Ferrer in the first match of the night session. Two-time finalist Andy Murray faces Kei Nishikori of Japan.
Two of the so-called "Big Four," Roger Federer and Rafael Nadal, are already through to a marquee semifinal after winning through Wednesday.
Federer beat 2009 U.S. Open champion Juan Martin del Potro 6-4, 6-3, 6-2 in a quarterfinal marking his 1,000th tour-level match. Nadal rallied after losing the first set for a 6-7 (5), 7-6 (6), 6-4, 6-3 win over Tomas Berdych.
Their match on Thursday will be their 27th in all, but their first in a Grand Slam semifinal since 2005.