French Open Day 4-5

China's Zheng Ji returns the ball to Canada's Aleksandra Wozniak during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Wednesday, May 30, 2012. (AP Photo/Bernat Armangue)

Novak Djokovic of Serbia returns in his second round match against Blaz Kavcic of Slovenia at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/Michel Euler)

Serbia's Novak Djokovic returns the ball to Slovenia's Blaz Kavcic during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Wednesday, May 30, 2012. (AP Photo/Michel Euler)

Roger Federer of Switzerland returns in his second round match against Adrian Ungur of Romania at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/Michel Spingler)

Roger Federer of Switzerland returns in his second round match against Adrian Ungur of Romania at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/Michel Spingler)

Novak Djokovic of Serbia celebrates winning his second round match against Blaz Kavcik of Slovenia at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/Michel Euler)

Switzerland's Roger Federer returns the ball to Romania's Adrian Ungur during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Wednesday, May 30, 2012. (AP Photo/Michel Spingler)

Switzerland's Roger Federer clenches his fist as he defeats Romania's Adrian Ungur during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Wednesday, May 30, 2012. Federer won 6 3, 6 2, 6 7, 6 3. (AP Photo/Michel Spingler)

Svetlana Kuznetsova of Russia returns in her second round match against Chan Yung Jan of Taipei at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/Michel Spingler)

Svetlana Kuznetsova of Russia returns in her second round match against Chan Yung Jan of Taipei at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/Michel Spingler)

USA's Bethanie Mattek Sands returns the ball to compatriot Sloane Stephens during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Wednesday, May 30, 2012. (AP Photo/Christophe Ena)

Ana Ivanovic of Serbia blows a kiss to fans after winning her second round match against Shahar Peer of Israel at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/David Vincent)

Ball boys watch Croatia's Petra Martic celebrating her win over France's Marion Bartoli in their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Wednesday, May 30, 2012. (AP Photo/Michel Euler)

Venus Williams of the U.S. returns in her second round match against Agnieszka Radwanska of Poland at the French Open tennis tournament in Roland Garros stadium in Paris, Wednesday May 30, 2012. (AP Photo/Michel Spingler)

Poland's Agnieszka Radwanska backhands to USA's Venus Williams during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Wednesday, May 30, 2012. (AP Photo/Michel Spingler)

Bird of prey trainer and keeper Ludwig Verschatse, a Belgian national living in France, poses on center court with his buzzard Zyna at the French Open tennis tournament at the Roland Garros stadium in Paris, early Thursday, May 31, 2012. Eight birds of prey have been released at Roland Garros to hunt birds that have been causing problems on the courts. (AP Photo/David Vincent)

A doctor tends treats the back injury of Andy Murray of Britain in his second round match against Jarkko Nieminen of Finland at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. (AP Photo/Michel Euler)

Russia's Maria Kirilenko returns the ball to Czech Republic's Klara Zakopalova during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Thursday, May 31, 2012. (AP Photo/Christophe Ena)

Spain's David Ferrer returns the ball to France's Benoit Paire during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Thursday, May 31, 2012. (AP Photo/David Vincent)

Petra Kvitova of the Czech Republic throws a ball back to a ball boy as she prepares to serve in her second round match against Urszula Radwanska of Poland at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. (AP Photo/Bernat Armangue)

Britain's Andy Murray returns the ball to Finland's Jarkko Nieminen during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Thursday, May 31, 2012. (AP Photo/Michel Euler)

Jo Wilfried Tsonga of France clenches his fist after winning his second round match against Cedrik Marcel Stebe of Germany at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. (AP Photo/Bernat Armangue)

Jo Wilfried Tsonga of France serves in his second round match against Cedrik Marcel Stebe of Germany at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. (AP Photo/Bernat Armangue)

Germany's Angelique Kerber returns the ball to Belarus' Olga Govortsova during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Thursday, May 31, 2012. (AP Photo/David Vincent)

Rafael Nadal of Spain returns in his second round match against Denis Istomin of Uzbekistan at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. (AP Photo/Bernat Armangue)

Denmark's Caroline Wozniacki returns the ball to Australia's Jarmila Gajdosova during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Thursday, May 31, 2012. (AP Photo/Michel Euler)

Spain's Rafael Nadal throws a ball to the public after defeating Uzbekistan's Denis Estomin during their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Thursday, May 31, 2012. (AP Photo/Bernat Armangue)

Jelena Jankovic of Serbia returns in her second round match against Varvara Lepchenko of the U.S. at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. (AP Photo/David Vincent)

The sunshade of the lens frames spectators with hats watching the match between Paul Henri Mathieu of France andJohn Isner of the U.S. on Philippe Chatrier center court at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. (AP Photo/Michel Spingler)

USA's Varvara Lepchenko takes her cap as she defeats Serbia's Jelena Jankovic after their second round match in the French Open tennis tournament at the Roland Garros stadium in Paris, Thursday, May 31, 2012. Lepchenko won 7 6, 4 6, 6 4. (AP Photo/David Vincent)

Paul Henri Mathieu of France celebrates winning his second round match against John Isner of the U.S. at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. Mathieu won in five sets 6 7, 6 4, 6 4, 3 6, 18 16. (AP Photo/Michel Euler)

Paul Henri Mathieu of France celebrates winning his second round mtch against John Isner of the U.S. at the French Open tennis tournament in Roland Garros stadium in Paris, Thursday May 31, 2012. Mathieu won in five sets 6 7, 6 4, 6 4, 3 6, 18 16, in a match which lasted over 5 hours and 40 minutes. (AP Photo/Michel Euler)