The tournament's official Twitter account confirmed Williams' titanic victory, where she saw her fortitude tested to the extreme by a contender gradually clawing her way into the elite of world tennis:
One might have expected the 22-year-old Stephens to feel some sense of intimidation against the world No. 1, but there was no evidence to suggest as much with the manner in which she began her assault.
The youngster battled the odds to take a 1-0 lead after the first game, breaking the top seed's serve to leave the Roland Garros crowd in some state of shock as to just how comfortable she appeared.
Stephens looked capable of causing a greater upset than she did against Williams at the Rome Masters in May, where she slumped to a straight-sets defeat 6-4, 6-0.
The world No. 40 didn't end the surprise there, though. After holding her own serve, Stephens broke Williams for a second time, sparking the following reaction from Ben Rothenberg of the New York Times:
Stephens lost only three more points in the remaining two games of the opening set to further stun the French crowd, with Williams simply struggling to reach the same intensity that led her past Victoria Azarenka.
Adam Zagoria of SNY.tv showed what extra motivation Stephens had to take her place in the quarter-finals, seeking to break new ground after defeating the older Williams sister, Venus, in the first round:
That little piece of history looked likely, as a downtrodden world No. 1 let the fleeting points of the first set evade her grasp, per BBC Sport's Russell Fuller:
Stephens perhaps didn't contemplate claiming the opening set by a margin of five games during her preparations for the fixture, but a cool demeanour was required in order to see out the match.
Rothenberg provided a glance at some telling statistics to sum up the first set, where Williams was perhaps her own worst enemy in committing a high number of unforced errors:
Perhaps predictably so, Williams returned with a vengeance in the second set and took a more aggressive stance with her serve, a sleeping giant having been awoken at Roland Garros.
The pair traded blows from the baseline, and each showed some impressive turns with the forehand until it was Williams' turn to break her foe's serve in the seventh game, taking a 4-3 lead in the second set.
Stefanie Gordon of Sports Illustrated emphasised the good that could come from a Stephens victory looking toward the future of American women's tennis, but keeping Williams at arm's length was proving increasingly difficult:
Almost to the amazement of Williams herself, Stephens took no backward step following that stumble and replied by breaking her opponent's serve for a third time in the match to draw level at four games apiece.
It was incredible and almost audacious to see the starlet match Williams' intensity, but tennis writer Tumaini Carayol noted the need to keep that fire in check, lest it spill over and leave her vulnerable:
Having struggled to do so earlier in the match, Williams was now finding the cross-court angles that had been evading her, but perhaps more importantly, Stephens was starting to contribute more errors of her own.
That drastic shift in the storyline aided Williams, a two-time French Open champion, in the fight back. The second set ended with Stephens overhitting a fairly routine forehand down the middle to draw level in sets.
Suppressing Williams' serve became a greater concern as the match wore on, and the 19-time Grand Slam singles champion appeared to grow in confidence as the pair again went to war in the third set.
In a battle to see who would blink first, it was Stephens who perhaps showed her inexperience in the fifth game as she dropped serve to give Williams a 3-2 lead. Tennis writer Chris Goldsmith touted this as the match's potential turning point:
Having been in this kind of scenario countless times in her career, Williams played with intelligence and came out the better of the two in long rallies, with Stephens perhaps showing her exhaustion more than the veteran.
Rothenberg even went as far as to call Williams' outlasting ability "legendary" as she protected herself to win the third set 6-3 and complete her comeback:
Stephens provided a test that even the world No. 1 may not have expected, and the fiery relationship between these two Americans entered a new phase thanks to Monday's superb contest.
"Not simple for me today. I'm surprised to win," Williams said afterward via Danielle Elliot of Busted Racquet. "Experience helped me."
In the end, though, it was Williams who proved her quality once again and recovered from a set down for her second French Open match in a row, seemingly intent on challenging for its crown the hard way. She'll face the 17th-ranked Sara Errani, who defeated Julia Goerges 6-2, 6-2 on Monday, in the quarter-finals.