'No person should ever be penalised professionally for having a child'
United States first daughter Ivanka Trump waded into the debate over Serena Williams's lack of a seeding at the French Open, tweeting that the women's tour needed to change its rules for players that take maternity leave.
Williams was world number one before leaving the tour last year to have a baby but the 23-time Grand Slam champion enters Roland Garros ranked 453rd.
The three-times French Open champion was not granted a seed by tournament organisers, triggering criticism from women's groups and tennis pundits.
"This is ridiculous. @SerenaWilliams is a formidable athlete (best ever!) and loving new mother," Trump, daughter of US President Donald Trump, wrote on Twitter.
"No person should ever be penalised professionally for having a child! The #WTA should change this rule immediately. #FrenchOpen."
Williams returned to the professional Women's Tennis Association (WTA) tour in March at Indian Wells in Southern California.
She won her first two matches before losing to sister Venus Williams. Two weeks later, she fell to Japan's Naomi Osaka in the opening round of the Miami Open.