The WTA Tour is an elite professional tennis circuit organised by the Women's Tennis Association (WTA).
Serena will restart her tennis career on the WTA tour next week after missing nearly a year following the birth of her first child.
Elina Svitolina emerged victorious at the winner-takes-all Tie Break Tens event at Madison Square Gardens in NY.
She won a record seven French Opens and reached the semifinals or better in 52 of 56 majors.
The 36-year-old has not played on tour since winning the 2017 Australian Open - the 23rd grand slam singles title of her outstanding career.
Ms Williams said she is preparing to return to the WTA Tour six months after giving birth.
She gave birth to her daughter on September 1 and has been working on her match fitness ever since.
"I think everyone should have high expectations", Williams said in an on-court interview after her loss. Madison Keys, who reached the US Open final past year, and Lauren Davis, who had triple-match point on top-ranked Simona Halep at the Australian Open, came through her academy.
"Serena's target will be to win grand slams", he told WTAtennis.com.
"My main thing is I would love for my daughter to be around with me doing great and playing unbelievable so it definitely gives me some motivation".
"There are three Grand Slams left this season".
Navratilova added that Williams' style of play means she will soon be competing at her best level. She said she was having fun playing again and was excited for the future.
"I just can not bet against her", she said in a recent phone interview with The Associated Press. A year ago this week is when we got "This Is Us", created for the brand in Turkey, and "What Are Little Girls Made Of?" from Russian Federation, two ads that took aim at outdated cultural norms. "It's always tough to transfer the work we do in the offseason, so this was a good sign that I'm moving the right way and I'm very, very happy that I played good tennis throughout the beginning of the year and just from here I can go only up". "She can still have a great year".