There were high hopes that the 44-year-old wildcard would become the oldest woman to win a singles match at the All England Club since Martina Navratilova achieved the feat aged 47 in 2004, but Joint had other ideas.
The 20-year-old, who was not even born when Williams won the first seven of her 23 Grand Slam singles titles, blocked out all the hullabaloo surrounding her opponent's comeback to produce the most notable victory of her fledgling career.
Joint walked on to Centre Court on the back of winning just one match in her last 12 tournaments, but by the time she walked off, she was basking in the glory of delivering a brutal knockout blow to one of the greats of the sport.
"I don't know what just happened to be honest," Joint told the cheering Centre Court crowd.
"I've been dreaming about this moment since I was a little kid, so this is pretty crazy."
Playing her first competitive singles match since the 2022 US Open, the American great might have been wondering if she had made the right call to accept a wildcard when she struggled to produce the kind of firepower that used to flatten rivals such as Joint.
With Williams making her first tentative steps back into prime time tennis, the 87th-ranked Australian came out swinging to rattle her American idol during the opening set exchanges.
However, the woman who John McEnroe hails as "the GOAT" and "one of the best athletes - male or female - in any sports" would not go quietly, and her roars of "C'mon" could be heard far and wide as she fought back from match point down to snatch the second set in a tiebreak.
However, Joint did not let that setback shatter her confidence or throw her off stride.
Around 45 minutes later, she was holding aloft her arms in victory after Williams ended one of the most talked-about comebacks in sporting history by swiping a service return long.
"I didn't get much to sleep last night. I was up till 2 a.m. just thinking about walking out," Joint said, still grinning from ear to ear.
"My legs weren't moving... she has such an aura, she's such a legend. I really don't know how I got a pretty good start in the match."
Joint will next play Filipino 29th seed Alexandra Eala.