Chinese tennis star Li Na speaks during a press conference about her retirement, at the Wuhan Open tennis tournament in Wuhan, in China's Hubei province on September 23, 2014. AFP PHOTO/Greg BAKER

Chinese tennis star Li Na reacts during a press conference about her retirement, at the Wuhan Open tennis tournament in Wuhan, in China's Hubei province on September 23, 2014. AFP PHOTO/Greg BAKER

Chinese tennis star Li Na waves to the crowd as she walks off center court after a ceremony marking her retirement, at the Wuhan Open tennis tournament in Wuhan, in China's Hubei province on September 23, 2014. AFP PHOTO/Greg BAKER

LONDON, ENGLAND - JUNE 19: Li Na attends the WTA Pre-Wimbledon party at Kensington Roof Gardens on June 19, 2014 in London, England.CAP/PL ??Phil Loftus/Capital Pictures

(140126) -- MELBOURNE, Jan. 26, 2013 (Xinhua) -- Li Na of China poses with the trophy on Brighton Beach in Melbourne, Australia, on Jan. 26, 2014. Li Na defeated Dominika Cibulkova of Slovakia in the women s singles final at the 2014 Australian Open tennis tournament and claimed the title on Jan. 25. (Xinhua/Li Jundong) (SP)AUSTRALIA-MELBOURNE-TENNIS-LI NA PUBLICATIONxNOTxINxCHN Melbourne Jan 26 2013 Xinhua left Na of China poses with The Trophy ON Brighton Beach in Melbourne Australia ON Jan 26 2014 left Na defeated Dominika Cibulkova of Slovakia in The Women s Singles Final AT The 2014 Australian Open Tennis Tournament and claimed The Title ON Jan 25 Xinhua left SP Australia Melbourne Tennis left Na PUBLICATIONxNOTxINxCHN

China's Li Na celebrates after victory in her women's singles final match against Slovakia's Dominika Cibulkova on day thirteen of the 2014 Australian Open tennis tournament in Melbourne on January 25, 2014. IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE AFP PHOTO / MAL FAIRCLOUGH

(140125) -- MELBOURNE, Jan. 25, 2014 (Xinhua) -- Li Na of China hits a return during her women s singles final match againstDominika Cibulkova of Slovakia at 2014 Australian Open tennis tournament in Melbourne, Australia, Jan. 25, 2014. (Xinhua/Bai Xue) (SP)AUSTRALIA-MELBOURNE-TENNIS-WOMEN S FNIAL-LI NA PUBLICATIONxNOTxINxCHN Melbourne Jan 25 2014 Xinhua left Na of China Hits A Return during her Women s Singles Final Match Cibulkova of Slovakia AT 2014 Australian Open Tennis Tournament in Melbourne Australia Jan 25 2014 Xinhua Bai Xue SP Australia Melbourne Tennis Women s left Na PUBLICATIONxNOTxINxCHN

(140125) -- MELBOURNE, Jan. 25, 2014 (Xinhua) -- Li Na of China hits a return during her women s singles final match againstDominika Cibulkova of Slovakia at 2014 Australian Open tennis tournament in Melbourne, Australia, Jan. 25, 2014. (Xinhua/Li Jundong) (SP)AUSTRALIA-MELBOURNE-TENNIS-WOMEN S FNIAL-LI NA PUBLICATIONxNOTxINxCHN Melbourne Jan 25 2014 Xinhua left Na of China Hits A Return during her Women s Singles Final Match Cibulkova of Slovakia AT 2014 Australian Open Tennis Tournament in Melbourne Australia Jan 25 2014 Xinhua left SP Australia Melbourne Tennis Women s left Na PUBLICATIONxNOTxINxCHN

TOPSHOTS Li Na of China poses with the winner's trophy following her victory over Dominika Cibulkova of Slovakia in the women's singles final on day 13 of the 2014 Australian Open tennis tournament in Melbourne on January 25, 2014. AFP PHOTO / PAUL CROCK IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE

(FILES) This file picture taken on January 25, 2014 shows China's Li Na playing a shot against Slovakia's Dominika Cibulkova during the women's singles final on day 13 of the 2014 Australian Open tennis tournament in Melbourne. China's two-time Grand Slam-winner Li Na is poised to retire, state media reported on September 18, 2014, in a move which would bring down the curtains on Asia's most successful tennis career. AFP PHOTO / SAEED KHAN / FILES -- IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE

(FILES) This file picture taken on on January 25, 2014 shows China's Li Na posing with the trophy after her victory against Slovakia's Dominika Cibulkova during the women's singles final on day 13 of the 2014 Australian Open tennis tournament in Melbourne. China's two-time Grand Slam-winner Li Na is poised to retire, state media reported on September 18, 2014, in a move which would bring down the curtains on Asia's most successful tennis career. AFP PHOTO / SAEED KHAN / FILES -- IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE

(FILES) China's Li Na celebrates her victory against Slovakia's Dominika Cibulkova during the women's singles final on day 13 of the 2014 Australian Open tennis tournament in Melbourne on January 25, 2014. China's two-time Grand Slam-winner Li Na announced her retirement on September 19, 2014, saying injuries had forced her to end her career. AFP PHOTO / SAEED KHAN -- IMAGE RESTRICTED TO EDITORIAL USE - STRICTLY NO COMMERCIAL USE

In this photo released by Tennis Australia, Li Na of China poses with a Chinese flag at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 24, 2014. Li faces Dominika Cibulkova of Slovakia in the women's singles final Saturday. (AP Photo/Tennis Australia, Fiona Hamilton)

In this photo released by Tennis Australia, Li Na of China poses with a Chinese flag at the Australian Open tennis championship in Melbourne, Australia, Friday, Jan. 24, 2014. Li faces Dominika Cibulkova of Slovakia in the women's singles final Saturday. (AP Photo/Tennis Australia, Fiona Hamilton)

Li Na of China returns a shot to Victoria Azarenka of Belarus during their tennis match at the WTA Championship in Istanbul, Turkey, Friday, Oct. 25, 2013. The world's top female tennis players compete in the championships which runs from Oct. 22 until Oct. 27. (AP Photo)

China's Li Na celebrates beating Italy's Roberta Vinci during their fourth round women's singles match on day seven of the 2013 Wimbledon Championships tennis tournament at the All England Club in Wimbledon, southwest London, on July 1, 2013. Li won 6-2, 6-0. AFP PHOTO / GLYN KIRK - RESTRICTED TO EDITORIAL USE

Li Na of China celebrates after defeating Dominika Cibulkova of Slovakia during their women's singles final at the Australian Open tennis championship in Melbourne, Australia, Saturday, Jan. 25, 2014.(AP Photo/Aijaz Rahi)

China's Li Na celebrates after defeating Russia's Maria Sharapova in their semifinal match at the Australian Open tennis championship in Melbourne, Australia, Thursday, Jan. 24, 2013. (AP Photo/Aaron Favila)

Bildnummer: 12499630 Datum: 22.01.2013 Copyright: imago/GEPA pictures TENNIS - WTA, Australian Open 2013 MELBOURNE,AUSTRALIEN,22.JAN.13 - TENNIS - WTA Tennis Damen Tour, Grand Slam, Australian Open. Bild zeigt Na Li (CHN). PUBLICATIONxNOTxINxAUTxSUIxITAxSWE ; Tennis x0x xkg 2013 quer premiumd Image number 12499630 date 22 01 2013 Copyright imago GEPA Pictures Tennis WTA Australian Open 2013 Melbourne Australia 22 Jan 13 Tennis WTA Tennis women Tour Grand Slam Australian Open Picture shows Na left CHN Tennis x0x xkg 2013 horizontal premiumd

Chiness tennis star Li Na (C) walks the cat walk during the Thai silk fashion show in Thailand's resort seaside town of Hua Hin on December 28, 2012. Azarenka will play an exhibition match with Li Na at the Hua Hin World Tennis Invitation on December 29. AFP PHOTO / PORNCHAI KITTIWONGSAKUL