Williams' victory at the Australian Open in 2017 was her 23rd Grand Slam title - the most in the Open era, and one shy of the all-time record held by Australian Margaret Court.
In other World Group matches this weekend, the Czech Republic will require top performances in Prague from a highly experienced quartet including double Wimbledon champion Petra Kvitova to overcome a strong Swiss team for whom Belinda Bencic, who defeated Venus Williams at the Australian Open, is in excellent form.
The former No. 1 seed and teammate Laura Davis will face the Netherlands' Lesley Kerkhove and Demi Schuurs in the second and final match on Sunday.
Five months after becoming a mother, Serena Williams is ready to return to competitive tennis for the first time since her 2017 Australian Open title.
"She's been out becoming a new mom, and she's looking to get back into playing", US captain Kathy Rinaldi said earlier this week. "The thing about Serena is she's never going to come back unless she feels she's where she wants to be tennis-wise, physically and mentally".
"It goes unsaid 25 is obviously something that I would love, but I hate to limit myself".
Venus Williams has been impressed with her younger sister's parenting skills.
Venus Williams was asked how motherhood had changed her sister. "But she's definitely remained just very youthful and childlike at heart".
"She might go out a little less", Venus said before breaking into a grin.
She mentioned there are "moments that have just been hard, getting back out there doing it every day".
But Williams, whose triumph in Melbourne a year ago gave her an Open-era record 23rd grand slam - one shy of the all-time record held by Australian Margaret Court - still has a desire to compete in tennis's blue riband events.
"I think she's smart to take her time and not to play Australia", ESPN analyst and 18-time Grand Slam singles champion Chris Evert said last week.
Green, a home-schooled student from Asheville, was chosen to select names out of the Fed Cup trophy that decided the draw.