Serena Williams' claims of sexism in the US Open final have been backed by the governing body of women's tennis. WTA Chief Executive Steve Simon said the umpire showed Williams a different level of tolerance of Saturday's outbursts than if she had been a man. Umpire Carlos Ramos penalised Williams after seeing her coach making a hand gesture. She was then penalised further for breaking her racket and calling the umpire a 'thief'. Her coach later admitted that he had been trying to coach her by using the hand gesture. Is she a victim of sexism? Or was this an unacceptable tantrum by a player who should know better?