Aged 39, Williams is considered Wimbledon royalty as she has been part of the All England Club family for over two decades, having won the singles title five times — including two before Gauff was even born.
But Guaff, the youngest player to qualify for the main draw in the professional era, was in no mood to play a lady-in-waiting as she made a mockery of the 24-year-age difference and 269 ranking spots that separate her from Williams.
Playing a fearless brand of tennis that belied her young age, she bullied Williams into submission.
A break in the fifth game of the opening set, which included a delectable lob over the statuesque Williams, was enough to win her the first set.
The nerveless display continued in the second set and she sealed victory on her fourth match point when Williams netted a forehand.