Just 10 months after giving birth, and suffering life-threatening complications, Williams will be back in the Wimbledon final today.
It will be a rematch of the 2016 showpiece against Angelique Kerber that Williams won in straight sets.
This is just a fourth tournament back on tour for Williams, but she has made smooth progress, dropping just one set in her first six matches.
She is just one win away from matching Margaret Court’s record of 24 grand slam titles and is chasing an eighth success here.
But the 36-year-old believes she is still finding her way back to her best.
“I was expecting a few more baby steps myself,” she said. “But I still feel like I’m in that baby step place.
“I’ve said it all week, this is only my fourth tournament back. Every time I go out there, I want to take a giant step forward, keep taking giant steps, but keep improving.
“I don’t know what I expected from this tournament. I just expected to win a match, then win the next match.
“Whenever I go out there, I just try to win my match. That’s literally all I do.”
Her toughest test will be waiting in the final as Kerber is getting back to the form that saw her win two grand slams in the 2016 season.
It could have been three had she been able to get the better of Williams in the All England Club final, but the American triumphed 7-5 6-3 in a competitive match.
“It’s her second final in three years,” added Williams. “That’s wildly impressive. Believe me, I know she wants to go out there and win.
“So do I. I think it will be just like the last final, it will be a really good final. Hopefully it will be a good result.”
Kerber’s form in 2016 saw her end Williams’ 186-week stint as world No 1, but it went downhill from there for the German.
In 2017 she failed to win a tournament, failed to get past the fourth round at any grand slam and slipped outside the world’s top 20.
But, after pairing up with coach Wim Fissette, she says Williams is not the only one making a comeback.
“I think it is a completely new match,” said Kerber. “We both learned a lot. She’s coming back. For me also, I’m coming back from 2017.
“It will be a new match. I know that I have to play my best, best tennis to beat her, especially on the grass, on the Centre Court, where she won so many titles here.
“I’m looking forward to playing against her. It’s always an honour to be playing against her. Serena is one of the best players in the world.
“We had so many great matches in the last few years. To see her back is great.”
Williams would not be the first woman to return for childbirth to win a grand slam.
The woman she is chasing at the top of the all-time major rankings, was the first.
Court won 21 grand slam singles titles before taking time out in 1971 and 1972 for the birth of her first child, son Daniel.
In 1973 the Australian triumphed at her home major as well as at the French and US Opens.
She had a daughter, Marika, in 1974 and again returned to the tour, but there would be no more grand slam trophy success.
And more recently, Kim Clijsters achieved the feat.
The Belgian’s professional tennis career appeared to be over, having been forced to retire at the age of 23 through injury and after giving birth to daughter Jada.
However, Clijsters completed a remarkable sporting comeback to win the 2009 US Open just 18 months after giving birth – becoming the first mother to win a grand slam singles title since Evonne Goolagong in 1980. Clijsters retained her title 12 months later before retiring in 2012 and has since had two more children.
Outside of tennis, Sheffield’s Dame Jessica Ennis-Hill won a world heptathlon title before adding Olympic silver to her collection in Rio after giving birth while Paula Radcliffe won the New York Marathon 10 months after giving birth.