She played like a seasoned veteran against Venus, improving as the contest progressed and committing a mere one unforced error in the entire second set.
After all that's gone on, why doubt her now? Some strayed long. Some nestled into the middle of the net.
It was dramatic - the freefall on Williams' side of the court.
But don't cry for Venus. After the match, in her typically taciturn way, she vowed to march on.
Over the Wimbledon fortnight, Muguruza played like a woman ready to shed the tag of a big-match underdog. It felt as if an icon was about to etch what could be a last gilded image into our collective memory banks. Williams, 37, was trying to become the oldest woman to ever win a major, but she just didn't have an answer for Spaniard. By any measure, it is fair to say she fell apart.
"Once I go to the big court, I feel good", she said.
Venus Williams' dream run at Wimbledon didn't yield the fairy-tale ending that many hoped to witness on Saturday.
It's disheartening that in this climate, where a historical wonder like LeBron is derisively referred to as "LeBum" by idiots who irrationally continue to worship at the alter of Jordan rather than appreciating the incandescent brilliance before us here and now in today's handsome game, that a collective understanding and appreciation of current genius gets lost in the microwaveable news cycles and fugazi sensationalism of a news culture more focused on clicks than quality. She didn't convert and that was the hinge point. This loss cut deeply. She didn't blame her age or her autoimmune disorder or anything else and she certainly doesn't need smarmy sports reporters to make excuses for her. She last won a singles title here in 2008, three years later she announced that she had been diagnosed with Sjogrens.
The coin toss was performed by 12-year-old Rebecca Jones, who was chosen for the honour by BBC Children in Need after losing her father to a brain tumour last year.
While it was no jaw-dropping surprise that Muguruza hoisted the Venus Rosewater dish on Centre Court - first time a women's final has been played under the closed roof, which amplified the sound of every pounded ball - the nature of this vanquishing over an opponent who'd progressed majestically through the draw was startling.
Venus Williams during her Wimbledon final match against Garbine Muguruza on Saturday
"Congratulations Garbine. I know how hard you work", Williams said.
About an hour later, in a hushed press room, she sat at a podium and grimly addressed an worldwide collection of reporters. Many thought the condition would end her career. I'm playing Venus here....' So I just keep fighting.
Williams was understandably subdued and deflated, but did not look to blame her illness.
"She played really well", she said, a flatness to her voice.
"It's great, but it doesn't give me the title quite yet". Since that moment I'm, like, I like grass and I'm going to look in a positive way.
The thrashing ended on an anticlimactic burp when, on match point, Williams hit a shot that landed long.
Martinez beat Martina Navratilova in 1994, and is also Spain's Fed Cup captain, so in the absence of Muguruza's regular coach, Martinez accompanied her compatriot here.
She knows sleep is something she won't get a lot of once the baby arrives but admits that quality rest will play a crucial role when she decides to return to the tennis court.
Immediately gracious in defeat, Williams said to her victor: "Well-done today, beautiful". She was 35 when she won this year's Australian Open. She's not young anymore.
"Two years ago I lost in the final to Serena and she told me one day I was going to maybe win, and hey, two years after here I am", she said courtside. "She just dug in there".
Well put. The grand dame of tennis will march on.