Seventh seed Ferreira, 31, showed the form which helped him beat second seed Sebastien Grosjean and fifth seed Mark Philippoussis in earlier rounds.
People can also fill out a seed request form online, and Hirshberg and her volunteers will send seeds directly to them.
The 16-year-old eighth seed looked in good form as she earned a hard fought 6-3 7-6 (7-3) victory.
In the second he made it to 5-5, showing occasional glimpses of his old form before the Swiss number two seed broke him.
Sharapova's semifinal opponent will be countrywoman Maria Kirilenko, after the 13th seed upset in-form world No. 8 Petra Kvitova with a 4-6 6-4 6-3 win.
Peer, who has been in fine form in 2010, beat top seed Caroline Wozniacki to reach the quarterfinals and said after the match that despite the controversies in the past she was receiving a good reception.
Paradorn Srichaphan showed flashes of his form of old as he upset sixth seed Nikolay Davydenko 6-4 7-5 6-3.
Nicholson will hope to continue his form in the last eight against third seed James Wade, who beat Vincent van der Voort 4-0.
Fifth seed Mardy Fish maintained the form he showed last week by moving into the second round with a comfortable win over Julien Benneteau.
However, 16th seed Berdych never approached the form that saw him stun the world number one, as well as French Open finalist Robin Soderling.
But she was unable to show the form that this week knocked out ninth seed Victoria Azarenka and Olympic champion Elena Dementieva as she was crushed 6-4 6-2 by world No. 26 Martinez-Sanchez.
The second seed has been in stuttering form in the early rounds, but extended her grand slam winning streak to 28 with a 6-1 6-2 victory over the Canadian in their fourth round match.
In the women's singles, seventh seed Jennifer Capriati continued her solid form, beating France's Nathalie Dechy, seeded 25, 7-5 6-1.
But fourth seed Ana Ivanovic was in sensational form as she crushed Tathiana Garbin 6-0 6-3 in the opening match of Wednesday's night session.
Monte Carlo finalist Guillermo Coria , the 13th seed, kept his recent good form going with a comfortable 6-2 6-2 win over Fernando Verdasco.
Eighth seed Victoria Azarenka was in excellent form in a 6-4 6-4 victory over Andrea Hlavackova of the Czech Republic and her next opponent will be South Africa's Chanelle Scheepers , who beat Russian Regina Kulikova 6-4 4-6 7-5.
Meanwhile, third seed Murray showed he is finding some form again after a poor season so far with a 6-2 6-1 crushing of Romanian Victor Hanescu.
Third seed Novak Djokovic, the in-form Nikolay Davydenko, 2008 finalist Jo-Wilfried Tsonga and last year's semifinalist Fernando Verdasco all progressed as the reputation for surprises at the season-opening grand slam continued to be undermined.
Second, seed stock is difficult to process into lethal form.
Another home player in fine form was British number two James Ward , who took 10th seed Mardy Fish all the way in a gruelling five-set match.
Former world number one Jelena Jankovic has slipped down the world rankings this year and she too has yet to win a major, while 13th-seed Ana Ivanovic has not shown anything like the form that saw her win last year's French Open.
Also through is sixth seed Victoria Azarenka of Belarus, who looked in impressive form as she thrashed ninth-seeded Dane Caroline Wozniacki 6-2 6-2.
French Open champion and fifth seed Francesca Schiavone of Italy continued her poor run of form since winning the title at Roland Garros and was beaten 6-4 6-4 by Russia's Elena Vesnina .
Bjorkman, who knocked out top seed Andy Roddick in the first round, was in inspired form against a dispirited Stoliarov, romping to a 6-1 6-0 win.
These offices, set up over the past 15 years, deploy artillery, rocket-launchers and aeroplanes to seed clouds with chemicals (usually silver iodide) that encourage droplets to form and fall where needed, or prevent the formation of destructive hailstones.
Home hopes were boosted by an easy straight sets win for seventh seed Andy Roddick over Thiemo de Bakker of the Netherlands while in-form Jo-Wilfried Tsonga of France was taken to three sets before beating Albert Montanes of Spain, 4-6 6-3 6-3.
Sixth seed Andy Roddick is also safely through -- with the home favorite in spectacular form as he crushed Sergiy Stakhovsky of Ukraine 6-2 6-1 in just 55 minutes.
Zheng will now face in-form Australian Samantha Stosur, who put out former world No. 1 Ana Ivanovic, the sixth seed from Serbia, 6-3 6-2, avenging a defeat at Wimbledon.
Top seed Djokovic, who lost to Nadal in last year's final, was in impressive form as he cruised past Argentine David Nalbandian 6-2 6-3 -- and he will now face either sixth seed Fernando Verdasco or Albert Montanes in the semifinals.
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