How much will tennis miss Serena Williams?

Danielle Rossingh for CNN | 5/15/2017, 11:26 a.m.
As Serena Williams chased a historic calendar grand slam in 2015, tickets for the US Open women's finals sold out ...
Serena Williams Margot Johnson photos

(CNN) -- As Serena Williams chased a historic calendar grand slam in 2015, tickets for the US Open women's finals sold out before the men's for the first time.

Although her quest to become the first player in 27 years to win four majors in the same calendar year ended at the semifinals in New York, it proved her status as not just one of the world's greatest tennis players but also one of sport's biggest attractions.

But with the world No. 1 now on maternity leave, what impact will her absence have on the sport she has dominated since winning her first major at the 1999 US Open at the age of 17?

"Exceptional athletes with rare and unique talent come along once in a decade," said WTA spokeswoman Heather Bowler. "The WTA has had over four decades, each marked by exceptional players, so we know these great and new champions will emerge, some already are, and we look forward to the future."

Rising stars and comebacks

Williams, whose publicist confirmed last month she was expecting a child with her fiance, Reddit co-founder Alexis Ohanian, is due to give birth in the fall.

Williams' last slam victory was at the Australian Open in January, where she beat her sister Venus in the finals.

Although that victory meant she leapfrogged Steffi Graf as the most successful player of the Open era with 23 majors, she remains one shy of tying the all-time record of Australia's Margaret Court and has said she plans to return to tennis in 2018.

The WTA pointed to the emergence of young rising stars such as US Open finalist Karolina Pliskova and the returns this season of former grand slam winners Victoria Azarenka, Petra Kvitova and Maria Sharapova.

Azarenka of Belarus is due back from maternity leave this summer, while Czech Kvitova is recovering from a hand injury caused by an intruder in her house before Christmas. Sharapova, of Russia, made her comeback after serving a 15-month doping ban for the banned heart drug meldonium last month.

"These three tennis superstars are coming back into a highly competitive field of talent," Bowler said.

"No one is bigger than the sport"

Still, in the US, tennis' biggest market which was valued at $5.94 billion in 2015 by the Tennis Industry Association, no star shines brighter than Serena.

The 35-year-old is known by about two-thirds of Americans, according to the The Q Scores Co. in Manhasset, New York, which measures consumer appeal.

Five-time major winner Sharapova, a global star in her own right and the world's most marketable female athlete for 11 years running until her doping ban last year, is known by about 40% of the US population.

"Serena is a really important part of the sport, but I don't think anybody is bigger than the sport," said Tim Crow, chief executive of London-based sponsorship agency Synergy whose clients include Coca-Cola and Mastercard.

Fewer Tour events

In the past three seasons, Williams has drastically reduced her playing schedule as she chased Graf's record and her absence will be most strongly felt during the four majors -- the Australian, French and US Open and Wimbledon.