STANFORD -- Andrea Petkovic was almost sorry about beating Venus Williams in the Bank of the West Classic quarterfinals Friday. Almost.
The engaging 26-year-old German was empathetic that she denied Bay Area tennis fans the possibility of a blockbuster -- an all-Williams sisters semifinal -- by outlasting Venus 6-1, 3-6, 7-5. She didn't blame them for the almost total lack of support she received during her victory while Williams received loud cheers for every winning point at Taube Family Tennis Center.
"I thought they hated me," Petkovic said. "Well, not hated me, they were just loving Venus obviously more and they wanted her to win more. I totally understood where they were coming from, because I would want a Venus-Serena semifinal myself as a tennis fan. But as a tennis player, I wanted myself to win."
But at least there was a consolation prize for fans and tournament organizers -- they received a fabulous match between top seed Serena Williams and fifth seed Ana Ivanovic in the late quarterfinal, and world No. 1 Serena is still alive after a gritty 2-6, 6-3, 7-5 victory before a packed house.
Without question, an all-Williams would have been one of the most anticipated matches in the long, illustrious history of this Bay Area event. It would have been the 25th meeting of the two sisters, arguably the greatest pair of siblings in sports history, and who knows? It might have set up as their last. After all, they've met only once in the past five years.
"I saw most of the match," said Serena of Venus' tough loss, which was eerily similar to her own except with a positive result. "I wish she could have pulled it through."
Instead, there's a new party-pooper challenge for Petkovic, ranked 18th in the world and seeded eighth here. She can become just the eighth woman to beat the Williams sisters in the same tournament when she plays Serena in an afternoon semifinal Saturday. No. 3 seed Angelique Kerber of Germany and unseeded Varvara Lepchenko meet in the evening semifinal.
For her part, Venus said Petkovic might have the capability to give Serena a battle, but there was little question that the elder Williams felt she gave away her match with 10 double faults and numerous unforced errors, a dispiriting about-face from her stirring straight-sets victory over Victoria Azarenka on Thursday night.
That said, Venus nearly pulled it out after an abominable first set in which she won just nine total points. Down 2-0 in the second set, she suddenly came alive to break Petkovic three times to win 6-3 and appeared to have the momentum when a seesaw third set was deadlocked at 5-5.
But Petkovic gathered herself, took a 6-5 lead with a love service game, then won four of five points on Williams' serve to take the match.
Venus seemed disappointed in herself that a possible meeting with Serena had been dashed.
"(Petkovic) played well, but I was not as on today as I was in previous days," Williams said.
The night match also came down to the final two games after Ivanovic staged two valiant comebacks to get back on serve in the third after being broken in the first and ninth games. After drawing even at 5-5 with a return break of Williams, Serena finally took over with a late burst of brilliance, breaking the Serbian's serve yet again and then drilling two aces while holding her own serve to close out the match.
Those aces were the most critical of her 10, because they helped offset eight double faults.
"I didn't get a lot first serves in (just 46 percent for the match), but I was going to keep hitting it and hopefully it would come through and it did," Serena said. "It definitely came through in that last game."
Ivanovic thought she let Williams off the hook.
"It's unfortunate the way it ended, but she's a great player," said Ivanovic, who tweaked a nerve in her hip late in the second set, which she said affected her the rest of the match. "She did what she had to do. It was an exciting match."
Kerber beat Garbine Mugurua 6-2, 6-1, while Lepchenko, who knocked off No. 2 seed Agnieszka Radwanska in the second round, ousted 19-year-old American qualifier Sachia Vickery 6-1, 6-0.
Friday's key results
No. 8 Andrea Petkovic d. Venus Williams, 6-1, 3-6, 7-5
No. 1 Serena Williams d. No. 5 Ana Ivanovic, 2-6, 6-3, 7-5
Saturday's semifinal matches
Petkovic v. Serena Williams,
No. 3 Angelique Kerber v. Varvara Lepchenko, 7 p.m.
Saturday's TV: 2 p.m., ESPN2; 7 p.m., Tennis Channel