Melbourne, Nov 8 - Serene Williams has revealed that she thinks her ass is "too big" for her to run a marathon.

The current No. 1 in women's singles tennis conducted a question-and-answer session with fans on Twitter responded to a query about whether she would follow in gal pal Caroline Wozniacki's footsteps and run the New York Marathon, News.com.au reported.

Williams also said that she's desperate she is to start a family and how she's not single by choice. (ANI)