On a day of persistent showers, the elder half of the sister act who transformedwomen's tennis rediscovered a little sunshine after the darkest two years of her life when she powered into the Wimbledon final.
Serving big, hitting big, shrieking big, she defeated reigning champion Maria Sharapova 7-6, 6-1 in a match of stunning quality.
Not only was it family revenge for the defeat of sister Serena by a 17-year-old Sharapova in last year's final, it was the end of a nightmare.
She suffered a stomach injury in her last Grand Slam final here two years ago, sidelining her for six months. The former world No 1 plummeted and beat only one topfive player in the last two years. Moreover, one of her sisters was murdered.
At the point of victory, when Sharapova slashed a backhand wide, the Williams joy washed around Centre Court.
She raised both arms to the brooding skies, skipped a few girlish steps and then jumped repeatedly in the air.
Up in the players' box, dad Richard snapped away with his camera, capturing the moment when his daughter reached her fifth Wimbledon final.
"I was so excited to be playing on Centre," Williams said. "This was the place to do it. I've just been raising my form.
"I love this tournament. This is the surface for me. I've just been working hard with my mom and my dad, making sure I listen and not be a hard-headed kid."
She said she had been inspired by a message from sister Serena, who lost in the third round, saying: "Serena sent me an e-mail telling me what to do and to stay in there and play my game and that I was the best. I guess I took that to heart.
"I have a good record here. Last year, I had an unfortunate match. This year, it's kind of fallen into step."
It was a simple description which went nowhere near to doing justice to the feat of the No 14 seed, who came into this tournament unheralded and has reached the final without losing a single set.
She had saved her best for Sharapova and a match which was switched from Court One after a four-andahalf hour rain delay.
It gave Williams the chance to redeem herself on the court she loves most and she did so quite brilliantly.
The first set was a wonderful example of the modern power of women's tennis, two big-hitters swinging from the hips without the slightest inhibition.
Sharapova was first to blink in the sixth game, one wondrous 11-stroke rally and two sizzling Williams backhands giving the American the break.
It might have been enough against many opponents but Sharapova is the grittiest, most determined of opponents. In the ninth game, she saved two set points and then produced the power and precision to break back.
The 'shriekometer' was registering record decibel levels as both women strained every sinew into the inevitable tiebreak. No-one on Centre Court was complaining about the grunting. They were too busy marvelling at the rallies.
While Williams stepped up a level, however, Sharapova erred and Williams took the breaker 7-2.
It was the first set the Russian had dropped in this tournament and it appeared to have shaken the Sharapova psyche when she lost her first service game of the second set.
Williams was crashing down serves at 117mph and, while Sharapova forced two break points in the second game, the Williams backhand was up to the task.
The scoreboard might suggest the second set was a walkover but it was anything but and, even in the sixth game, Sharapova might have fought her way back if she had not chosen perhaps the worst drop shot of her career.
The game lasted nine minutes, Sharapova squandered two break points and when Williams collected it to take a 5-1 lead, the victory looked sure.
The rain began to fall. Might Sharapova have an ally in the sky? It wasn't to be, too many wild backhands allowing Williams two match points. It was all over when another Russian backhand went wide.