Gauff's family said she dug deep, fought the nerves and began to play.
During an impossibly tense tiebreak, Gauff showed calmness well beyond her tender years to take it 9-7.
This may sound like a broken record, but if you though Gauff was impressive against 39-year-old Venus Williams in her first match, wait till you saw her poise in the second. And they were just as excited about the 15-year-old's win as everyone at center court.
What advice does Williams have for Gauff? The 15-year old American saved two match points in the second set en route to a Round of 16 showdown with seventh seed Simona Halep.
"I wouldn't be here if it wasn't for her - I told her she was so inspiring and I've always wanted to tell her that but I've never had the guts to before".
"It's a big thing right now, so I wasn't really expecting a lot of people to be on my side", she said sadly. "She didn't hit her way through Hercog so to speak, she was slicing the ball back and giving Hercog no pace suddenly".
Hercog's first match point came and went on Gauff's serve at 3-5, with a second arriving a game later when she was serving for the match. From there, Gauff worked her magic in the third and final set, pulling off the improbable win.
Later Candi and husband Corey were busy posing for pictures for spectators near the players' locker rooms.
Barty and Serena Williams dominate to enter Wimbledon fourth round
Knee problems that have plagued her season have yet to resurface in London , which bodes well for the challenges ahead. Serena broke in the sixth game, though, and clinched the set at the third time of asking by making a forehand victor .
Then, by upsetting five-time champion Venus Williams, who is 39, in the first round of the main event, Gauff became the youngest woman to win a match at the All England Club since 1991, when Jennifer Capriati reached the semifinals at 15.
"I can see myself more far, but I will try not to think about it".
"I think it's the worst decision I have had to make, especially midtournament".
But no matter. Being tweeted by Michelle Obama, Jaden Smith and Samuel L Jackson among others more than made up for losing her mixed doubles match with Jay Clarke 6-1 6-4 to Robert Lindstedt and Jelena Ostapenko.
Said Murray: "I think toward the end of the match, when you're kind of in control on the scoreboard, it's easier to sort of relax and enjoy it". Gauff didn't let her. Miss Tina Knowles, Beyonce's mum, posted me on Instagram.
Despite her high-profile, continued participation in singles, Gauff stuck to her routines on Saturday. "I thought there was a small chance she would even get the wild card to play in qualifying, but we thought we would just put in the paperwork and see what happened".
Gauff would race out to a 4-1 lead but eventually lost serve as Hercog evened the match at 5-5. "That's probably not true, but in my mind's eye, I'm going to go with that".