Serena Williams has penned an open letter calling out what she sees as double standards faced by women in sports.
The 22-time Grand Slam champion writes that women ''are constantly reminded'' they aren't men. She says people call her one of the ''world's greatest female athletes,'' but notes that male athletes such as LeBron James, Roger Federer and Tiger Woods aren't described by their gender.
Williams says the equal pay issue frustrates her because women ''have done the same work and made the same sacrifices as our male counterparts.''
She says women ''must continue to dream big'' to ''empower the next generation of women to be just as bold in their pursuits.''
The letter was published in Porter Magazine and republished by British newspaper The Guardian .