Serena and Venus Williams were among six players nominated for the US Olympic women's team to compete in next month's London Olympics, the US Tennis Association (USTA) said on Tuesday.
Maria Sharapova defeated French qualifier Stephanie Foretz 6-1, 6-4 while Venus Williams survived British wildcard Naomi Cavaday.
Wimbledon champion Venus Williams will get back into serious action on Saturday when she plays the second singles rubber against Nadia Petrova, in the Fed Cup semi-final.
The two players bowed out in the quarter-finals of the Advanta Championships in Philadelphia.
Asked if she could have all her titles and Venus all hers without having ever had to play each other, Serena said she would happily accept that deal.
Venus Williams, who had advanced to the quarter-finals, pulled out of the China Open with a left knee injury
Second seed Venus Williams tumbled out of the Family Circle Cup on Thursday, succumbing 6-4 7-6 to big-serving German Sabine Lisicki in the third round. The American, who had to battle the previous day before beating Indian Sania Mirza in three sets, lost the match in 87 minutes after the 16th-seeded German took the tiebreak 7-5.
Rafael Nadal took a while to warm up but made an impressive start to his Wimbledon title defence with a 6-4, 6-2, 6-2 win over American Michael Russell as the 125th championships began in fine weather on Monday.
Venus Williams battled past fellow American Laura Granville 7-6, 6-4 to reach the Memphis International semi-finals
Third seed Venus Williams booked her place in the quarter-finals at Wimbledon on Monday after Serbian 13th seed Ana Ivanovic retired injured in their fourth-round clash.
American Venus Williams marked her return from an abdominal injury with an impressive 7-5, 5-7, 6-3 victory over Germany's Andrea Petkovic at the Eastbourne championships on Monday.
The third seeded Russian rallied to beat the American to reach the semi-finals of the Warsaw Cup.
After a long rain delay Germany's Sabine Lisicki made quick work of Venus Williams, strolling into the second round of the Rogers Cup on Monday after routing the American 6-0 6-3.
With Serena bidding to become just the fourth woman to win all four grand slams in the same year, the US Open hype machine that already had been in top gear is now set to crank into overdrive.
The 19-year-old went down 3-6, 3-6 to Venus Williams in the quarter-finals of the Watson Water Champions Challenge.
Venus Williams beat Jill Craybas 6-3, 6-1 to book her spot in the Japan Open second round.
Venus Williams showed that, almost a year after her health scare, she has the stamina needed as she battled for two hours 23 minutes to beat Russia's Maria Kirilenko 6-3, 6-7, 6-2 at the Cincinnati Open on Tuesday.
Venus Williams secured her place in the semi-finals of the WTA Championships when she completed her round-robin matches with a comprehensive 5-7, 6-1, 6-0 win over her sister Serena on Thursday. It was the first time Serena had lost a set 6-0 since the 2007 Miami final, after which she recovered to defeat Justine Henin for the title.
The French top seed beat the American 4-6, 7-5, 6-4 in the final of the Antwerp Diamond Games.
As she did two years ago when she came in at number 14, the imposing American made a mockery of a low seeding.
Serena and Venus Williams both booked their places in the third round of the Sony Ericsson Open with victories at Key Biscayne in Miami on Saturday. World number one Serena did not sparkle but still had little trouble in her 6-2, 6-3 victory over compatriot Alexa Glatch. Serena's sister Venus got off to a slow start but found her form to defeat spirited Israeli Shahar Peer 6-3, 6-3.
Venus Williams avoided another early exit with a routine win over fellow American Alison Riske at the Volvo Car Open in South Carolina while Swiss second seed Belinda Bencic was ousted by Russian qualifier Elena Vesnina.
The world No 32 cited a left wrist injury as the reason for her withdrawal.
American sisters Serena and Venus Williams powered on towards a likely gold medal showdown with easy second-round wins in the Olympic singles.
Venus Williams survived a scare before beating Danish teenager Caroline Wozniacki while Virginie Razzano got the better of Italian Flavia Pennetta in the semi-finals of the Japan Open.
The former world number one beat Japan's Akiko Morigami 6-1, 2-6, 6-4 in the first round of the Memphis International.
Defending champions Serena and Venus Williams defeated Cara Black and Liezel Huber 6-4, 6-3 to win the Australian Open women's doubles title on Friday, maintaining the partnership's perfect record in grand slam finals.
Madison Keys continued to ride her wave of success, fuelled in part by celebratory chocolate biscuits, as she advanced to her first Grand Slam semi-final with a gutsy 6-3, 4-6, 6-4 victory over Venus Williams on Wednesday.
Defending champion Venus Williams eased into the third round of the Dubai Championships on Tuesday with a 6-2, 6-3 victory over Germany's Sabine Lisicki. Top seed Caroline Wozniacki had to recover from 1-5 and save a set point to defeat Slovak Dominika Cibulkova 6-2, 7-6 while second seed Svetlana Kuznetsova received a walkover when Spain's Anabel Medina Garrigues withdrew with a back injury.
Tournament officials said there was no heat rule in effect on Friday for the first time in three days, with cloud cover expected to bring cooler temperatures.
Five-times champion and second seed Venus Williams was stunned 6-2, 6-3 by Bulgaria's Tsvetana Pironkova in the quarter-finals of Wimbledon on Tuesday.
She beat sixth seed Ana Ivanovic in the first round of the Luxembourg Championship on Wednesday.
China's Li Na defeated a battling Venus Williams 7-5, 3-6, 6-1 to reach the final of the Cincinnati Open on Saturday after an enthralling two-hour nine minutes encounter.
While Venus has been doing pretty well on-court, the 37-year-old is busy with some off-court chores and it reads - online shopping for the newborn.
IMAGES from the Australian Open matches played at Melbourne Park in Melbourne on Thursday.
The Williams sisters Serena and Venus fell by the wayside in the fourth round at Wimbledon on Monday. Defending champion Serena was beaten 6-3, 7-6 by Frenchwoman Marion Bartoli while five-time champion Venus was outplayed by Bulgaria's Tsvetsana Pironkova 6-2, 6-3.
