Down a set, trailing 2-5 and serving the eighth game, the 15-year-old American was digging deep to find something to shift the momentum. Then, serving at 40-all, it happened -- an amazing point won by Gauff that led her to take the game, the second set and, eventually, the match.
Said ESPN television analyst Chris Evert: "Remember that point. ... Tennis matches can turn on a dime." And this one sure did. We break down the stretch that led to Gauff's big victory on Centre Court:
Saving Hercog's first match point
Leading by a set and 5-2, Hercog hit a great pass down the line to move to 30-40 on the Gauff serve and set up match point. But after a long rally, Gauff moved forward to a short ball and threaded a sliced backhand inside-out and onto the sideline. Hercog challenged, but Hawk-Eye showed it was in.
"I always knew that I could come back, no matter what the score is," Gauff said after the match. "And I just kinda went for my shots, and I'm happy that slice down the line went in."
Saving Hercog's second match point
A big ace from Hercog set up a second match point at 5-3, but the Slovenian buckled and double-faulted. She saved one break point with a huge forehand but couldn't save another, so then Gauff was back on serve.
Hercog's mangled smash
Having regained her poise to hold serve and lead 6-5, Hercog pressed on the opening point of the Gauff serve. Under pressure, the teenager hoisted a high lob, but it was short, inside the service box. Hercog let it bounce, only to then smash it wildly, long.
Second-set tiebreak: Hawk-Eye challenge
Coco fights her way into the round of 16
Coco Gauff rallies to defeat Polona Hercog in three sets to advance to the fourth round of Wimbledon.
Down 3-5 in the second-set tiebreak, Gauff rallied to put the tiebreak (her first at Wimbledon) at 6-all. On the next point, Hercog stopped in the middle of the rally when she believed Gauff's shot went long. It was not the right time to challenge, as the review showed the ball clipped the line. After an exchange of points, many of which included slices from both sides (drawing gasps from the crowd), Gauff finally edged Hercog 9-7 to force the third set.
Hercog's second-set lapse
Hercog's serve was nigh-on unbreakable in the opening set -- she was 8-for-8 with a 100% first-serve win percentage and won 84% of her second serve points (16 of 19).
However, those stats dropped significantly in the second set as Hercog's first-serve win percentage fell to 68% (15 of 22) with her second serve at just 62% (28 of 45).
The long, long wait
After a pulsating second set with emotions running high, Hercog called on the trainer to work on her left leg before the doctor came out. She then left the court for five minutes for a comfort break.
Five minutes can seem like an eternity. Gauff wrapped herself in a towel, put on a jacket and sat patiently in her chair. Hercog came back out; play eventually resumed; and, despite a sixth double fault, Gauff held serve to calm the nerves and ease herself into the match-winning set.
The topsy-turvy deciding set
With Hercog serving facing a break point at 1-2, Gauff returned a simple backhand -- it should have been bread and butter, but Hercog's loose forehand landed in the tramlines to gift her opponent the breakthrough.
However, Gauff then conceded the break with a netted backhand slice, and soon they were level at 4-4.
With Hercog serving again at 5-6, she scooped a low forehand long to bring up deuce. A slice rally ensued, before Hercog again netted with another unforced error on the forehand. With Gauff on match point, Hercog's high lob was too long, and her third consecutive lost point helped complete one of the biggest comebacks Centre Court has seen.
"Right now, I'm just super-relieved that it's over," Gauff said. "It was a long match, she was playing unbelievable; and it was my first match on Centre Court, so I guess people say Court 1's my court, but maybe Centre could be my court, as well."