Venus and Serena Williams through the years

Venus Williams of the US returns a ball to Paraguay’s Rossana De Los Rios on the first day of the Wimbledon Tennis Championships at the All England Tennis Club, in southwest London, on June 21, 2010.   (ADRIAN DENNIS, AFP/Getty Images)

Venus Williams of the US returns the ball to Paraguay’s Rossana De Los Rios on the first day of the Wimbledon Tennis Championships at the All England Tennis Club, in southwest London, on June 21, 2010.   (ADRIAN DENNIS, AFP/Getty Images)

Venus Williams of the US returns the ball to Paraguay’s Rossana De Los Rioson the first day of the Wimbledon Tennis Championships at the All England Tennis Club, in southwest London, on June 21, 2010.   (ADRIAN DENNIS, AFP/Getty Images)

Venus Williams of the US returns the ball to Paraguay’s Rossana De Los Rios on the first day of the Wimbledon Tennis Championships at the All England Tennis Club, in southwest London, on June 21, 2010.   (ADRIAN DENNIS, AFP/Getty Images)

Venus Williams of the US plays a return to Patty Schnyder Switzerland during their Women’s first round match in the French Open tennis championship  (PATRICK KOVARIK, AFP/Getty Images)

Venus Williams of the US plays a return to Patty Schnyder Switzerland during their Women’s first round match in the French Open tennis championship   (PATRICK KOVARIK, AFP/Getty Images)

Venus Williams of the US plays a return to Patty Schnyder Switzerland during their Women’s first round match in the French Open tennis championship   (PATRICK KOVARIK, AFP/Getty Images)

Venus Williams of the US plays a return to Patty Schnyder Switzerland during their Women’s first round match in the French Open tennis championship   (PATRICK KOVARIK, AFP/Getty Images)

Venus Williams of the US plays a return to Patty Schnyder Switzerland during their Women’s first round match in the French Open tennis championship at the Roland Garros stadium   (PATRICK KOVARIK, AFP/Getty Images)

Venus Williams of the US plays a return to Patty Schnyder Switzerland during their Women’s first round match in the French Open tennis championship  (PATRICK KOVARIK, AFP/Getty Images)

Serena Williams lunges for a shot during her 7-5, 6-3 victory Monday over 36th-ranked Kaia Kanepi of Estonia in the first round.   (Alastair Grant / Associated Press)

Defending champion Venus Williams rebounded from a tough first set to collect a 7-6, 6-1 victory over Naomi Cavady on Tuesday.  (Anja Niedringhaus / Associated Press)

Venus Williams joined her sister Serena as first-round winners with her victory Tuesday over Naomi Cavaday of Britain.   (Adrian Dennis / AFP / Getty Images)

Serena Williams returns a volley against Vera Zvonareva during her match at the JP Morgan tennis tournament at the Home Depot Center in Carson on July 23, 2004.  (Lori Shepler / LAT)

Serena Williams celebrates her win against Daniela Hantuchova of Slovakia.  (GERRY PENNY / EPA)

POISED: Serena, left, and Venus Williams, could meet in a Grand Slam tournament for the first time since Wimbledon in 2003.  (Anja Niedringhaus / AP)

MELBOURNE SUPREMACY: Serena Williams, who earlier in the week was being asked whether her game was in decline, had all the answers in the Australian Open final against Lindsay Davenport.  (Clive Brunskill / Getty Images)

Tennis player - Serena Williams  (Richard C. Soria/Zap2it.com)

EXULTATION: Venus Williams celebrates after defeating Wimbledon defending champion Maria Sharapova in semifinals.  (Odd Andersen / AFP / Getty Images)

Venus Williams showed her athleticism Monday by chasing down shots to the corners from Agnieszka Radwanska during a straight-set victory in the fourth round of the U.S. Open.   (Juile Jacobson / Associated Press)

Serena Williams acknowledges the cheers of the crowd after beating Severine Bremond in straight sets in the fourth round of the U.S. Open.  (Charles Krupa / Associated Press)

Venus Williams reacts after winning her semifinal match against Russia’s Elena Dementieva on Centre Court at Wimbledon.  (Anja Niedringhaus / Associated Press)

Serena Williams looks to her sister Venus after defeating her in the Wimbledon final in 2003.  (Odd Andersen / AFP / Getty Images)

Serena Williams poses as she arrives at the benefit gala for the Fulfillment Fund 25th Anniversary at the Fox Studios in Los Angeles.  (Damian Dovarganes / Associated Press)

Venus Williams shows off her Wimbledon trophy after defeating Justin Henin, 6-1, 3-6, 6-0.  (Gerry Penny / AFP)

Serena Williams got this return in play, but she committed 36 unforced errors, a pivotal factor in her 6-2, 6-4 loss to sister Venus at the U.S. Open.  (Jamie Squire / Allsport)

Venus, left, and Serena Williams hold the winners’ trophy after defeating Chanda Rubin of Lafayette, La., and France’s Sandrine Testud in the U.S. Open women’s doubles championship.  (Kathy Willens / Associated Press)

Venus Williams, left, and sister Serena raise their arms after their center court match at the Australian Open. Venus won, 7-6, 6-1.  (Rick Stevens / Associated Press)

Venus Williams makes her power pay off, winning the $800,000 Grand Slam Cup.  (Gary M. Prior / Allsport)

Venus Williams follows through on a return to Sandrine Testud of France during their match at the U.S. Open.  (Ron Frehm / Associated Press)

Serena Williams defeated Severine Bremond of France, 6-2, 6-2, on Monday to advance to the quarterfinals of the U.S. Open, and a meeting with her sister Venus.   (Al Bello / Getty Images)

Venus Williams stretches to hit a backhand volley against Agnieszka Radwanska during a straight-set victory on Monday in the fourth round of the U.S. Open.   (Justin Lane / EPA)

Serena Williams of the US serves to Ai Sugiyama of Japan during the third round of the US Open tennis tournament on August 30, 2008 at the USTA National Tennis Center in New York.   (TIMOTHY A. CLARY, AFP/Getty Images)