Unfortunately for the greatest sister act in sport, she was right.
Since the tears fell that day, Garbiñe Muguruza has reached two further grand slam deciders and won them both.
In doing so, she has become the first player in history to defeat both Williams sisters in major finals.
"It means a lot," the Venezuelan-born Spaniard told CNN Sport, having followed her 2016 French Open victory against Serena with a straight sets win
(7-5 6-0) over Venus at Wimbledon on Saturday.
"For me, it has an extra value to be able to beat the Williams sisters in the finals, because they are just so good.
"For me, it's proof of being literally the best player in the tournament."
Not many players could reel off nine straight games against a player of Venus's distinction.
Muguruza, though, did exactly that -- only dropping one set and 44 games throughout the entirety of this year's Wimbledon campaign.
"Congratulations Garbiñe, amazing," said a dignified Williams after the match. "I know how hard you work and I'm sure this means so much to you and your family. Well done today, beautiful."
If the final point of the final game was underwhelming -- with victory confirmed courtesy of a Hawk-Eye challenge -- the magnitude of sealing her second grand slam title in such circumstances is still only just sinking in.
Indeed, having been granted her wish to dance with the "elegant" Roger Federer at the Wimbledon champions' dinner, Muguruza has been rewatching the match on repeat.
"I love to see it right after because I want to see if it's true!" she said.
"When you're inside [Centre Court], it's so emotional that you don't even remember. Once I'm outside, I want to see myself.
"I'll probably watch a few more times during the week."
Muguruza knows she can't afford to revel too long in her victory.
Her celebrations were muted, consisting of some white wine with her team at a Spanish restaurant in central London before an early night.
She has, after all, been here before.
After conquering Serena in straight sets on the Parisian clay (7-5 6-4), Muguruza was humbled by a series of unheralded opponents -- from world No. 61 Kirsten Flipkens in the ensuing Mallorca Open, to Slovak qualifier Jana Cepelova in last year's Wimbledon second round.
She returned to Roland Garros this year intending to defend her title, but left in tears following an underwhelming last 16 defeat to home favorite Kiki Mladenovic, who was backed by a partisan French crowd.
Until Saturday, the 23-year-old Muguruza had failed to reach a single final since that watershed moment, struggling to meet her own high standards.
Now back in the top five of the WTA rankings, she has no intention of letting it slip.
"Hopefully it's going to help me," said Muguruza, reflecting on the tough times she's left behind.
"I learned that it's very hard to have the expectation to play like that every week, because then comes the frustration.
"I've got to be humble, and accept that the level I showed here is very hard to get.
"I have to work to get it, and not expect to have it."
Muguruza raised a few smiles on Centre Court when she said she had "grown up" watching her 37-year-old opponent.
Just six years old when Venus won her first Wimbledon crown, Muguruza nonetheless looks to be in as good a place as any to challenge the game's dominant duo going forward.
Only three active players (Serena, Venus and Maria Sharapova) can boast more Grand Slam titles than the Spaniard on the WTA tour.
"It's a nice position to be in, honestly," she said, having swiftly become a role model in both Spain and her native Venuezela.
"When a kid comes next to you and she's like 'Ooh, one day I want to be like you!' you're like 'Wow, that's so nice to hear!'
"To be able to make other girls play -- and hopefully in Latin America as well -- is very important to me."
Her own sense of wonder was clear as she saw her name, Miss G. Muguruza, on the prestigious Wimbledon Roll of Honour board.
"It was big," she said. "Every time I've walked through there, past the wall, I've seen all those names and thought 'hopefully my name can be there.'
"Yesterday they were putting it there and I realized: It's real."