Nadia Petrova battled back from 63 41 down to get past Sara Errani in a quarterfinal thriller.
WTA Staff

TOKYO, Japan - Quarterfinals Day at the Toray Pan Pacific Open began with a pair of absolute nail-biters, with Nadia Petrova and Samantha Stosur both moving through and setting up a semifinal clash at the Premier-level tournament.

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The No.17-seeded Petrova was the first of the pair to advance, though she had to pull off a Houdini act to do it - down 63 41 and double faulting to face a point for a 63 51 deficit, the Russian flipped the switch just in time, battling back to make it past No.6 seed Sara Errani in three grinding sets, 36 75 63.

"You never want to leave the court without giving everything you have, so even at a set and 4-1 down I still believed I could turn it around," Petrova said.

Petrova, who is currently ranked No.18 in the world but is a former World No.3, is through to her biggest WTA semifinal in three years, since Beijing in 2009.

The No.8-seeded Stosur defied a 1-10 head-to-head record against No.2 seed Maria Sharapova in the next match, mixing in spins and squash shots and rushing the net time and time again en route to a 64 76(10) win. Sharapova fought until the bitter end - Stosur originally led 64 53 and missed into the net on her first four match points - but it was fifth time lucky for the Australian, as Sharapova missed a forehand down the line wide on match point No.5.

"I lost nine points in a row from 5-3 up in the second set, but I knew I had to turn it around and not let that continue," Stosur said in her on-court interview. "I had a good start in the tie-break and it really helped me forget about all of that.

"It was a close tie-break. I had some match points - if you miss a few in a row you think about it, but I stayed positive and kept going for it, and it paid off."

Stosur has now won seven of her last 11 matches against Top 2 players.

Petrova leads Stosur in their head-to-head series, 5-3, though Stosur has won three of the last four meetings - and the Australian's 76(5) 67(5) 75 win at the US Open last year was the longest recorded women's match ever at the US Open, lasting three hours and 16 minutes. Stosur went on to win that title.

"Nadia's one of those players who, when you play each other, you seem to bring out the best in each other every time," Stosur said. "She had a very good win today, but if I can play well and play close to my best, I've got a shot."

The third quarterfinal was scheduled to be No.1 seed Victoria Azarenka against No.5 seed Angelique Kerber, but it never took the court as Azarenka was forced to withdraw from the tournament because of dizziness.

"I wasn't feeling well before this tournament and had real trouble focusing on the court yesterday - today I hoped I'd feel better but unfortunately not," Azarenka said. "Maybe this is just the end of a long year where I've played a lot of matches. I'm not really sure what's wrong, but I'll have tests to see what it is.

"I'm very sorry to be withdrawing. I would have loved to go out on the court and shown my best tennis, but my health is the most important thing. I want to come back here next year and show some good tennis to the Japanese fans."

No.3 seed Agnieszka Radwanska rounded out the final four with a 64 63 win over No.10 seed Caroline Wozniacki in the last quarterfinal of the day.

And just like that, No.3-seeded defending champion Radwanska is the favorite for the title - the other semifinalists are seeded No.5, No.8 and No.17.

"Of course, but the others are playing very well at this tournament, so the ranking doesn't really matter at this point," she said. "This is the semifinals of a big tournament and I'm playing Top 10 players, so it's always very difficult."

Radwanska leads Kerber in their head-to-head series, 3-2.