One and two might be gone, but seeds three and four look in ominous form before today's semifinals.
In the night match yesterday, Svetlana Kuznetsova wrapped up the last place in the quarter-finals with an impressive straight sets 6-4, 6-3 victory over Italian Sara Errani, pushing her record against the world No 45 to 5-0. That despite a first-serve percentage that should have crippled her chances.
"I didn't serve so well today," the Russian said, when asked what she needed to work on before today's match against in-form Chinese player Zheng Jie.
Zheng was a comfortable 6-2, 6-3 winner over Czech Lucie Hradecka.
Kuznetsova sent down eight aces and did not serve a single double fault, but a 41 per cent first-serve percentage means the other parts of your game have to be in excellent working order to beat the best players.
As it was, she got in the zone with her two-handed backhands and went through a spell where she never looked like missing.
On a day of remarkably one-sided quarter-finals, Kuznetsova's victory was overshadowed by an injury retirement of top seed Sabine Lisicki and a near flawless display by Flavia Pennetta.
After Wednesday's tortuous opening match on centre court, yesterday started with the Italian fourth seed's 67-minute 6-2, 6-1 romp over an overmatched Elena Vesnina.
In their five previous matches, two on hard courts, Pennetta had a one-match edge, so there was every expectation of a more competitive showing from the world's No 57.
Pennetta, though, is at the top of her game and it will be a tough outing for Angelique Kerber of Germany today.
"I played really well. I didn't make a mistake at all. I was serving so good and everything was perfect so there's not too much to say today," the fourth seed said. "I want to keep feeling the same sensation, but it will be tough because today was perfect."
Pennetta, the world No 20, would have struggled to envisage this scenario on Monday. She struggled so badly against Sorana Cirstea 6-4 7-6 (5), that the idea of being involved in the semifinals would have required vivid imagination.
Pennetta, 29, is one of the most engaging players on tour, having published a biography - Dritto al Cuore (Straight to the Heart) - last year.
In the book the Italian gives candid accounts of fellow players and reveals that she once challenged Anastasia Rodionova to a fight during a game of doubles. But the most searing passages are when she is discussing her relationship with former world No 1 Carlos Moya.
Pennetta discovered he was having an affair with Spanish television presenter Carolina Cerezuela and she recounts the agonising self-doubt that followed.
"I was trying to be numb towards life, not to feel pain. I did not even feel physical [pain]. A silly example: even when I was waxing, I did not even feel anything," she wrote.
Pennetta said she was asked to do it one year ago and she yes to the publishers because she wanted Italians to see behind the player and give the public a glimpse of the life of a tennis professional.
Physical, rather than emotional, pain was the theme of the all-German quarter-final, with No 1 seed Sabine Lisicki retiring with an abdominal injury at 15-30, 3-4 and one set down. That gave Kerber an easier than expected route to her semifinal showdown with Pennetta.
Pennetta lost to Kerber in the quarter-finals of last year's US Open.
"I remember that match really well," said a suddenly rueful Pennetta. "She was better than me. That's it."
Pennetta is still on target to win the singles-doubles quinella after her combination with Julia Goerges prevailed over Alize Cornet and Monica Niculescu in a super-tiebreak in the quarter-finals.