Australia were 38-10 down and set to record a losing margin against England that would eclipse the 24 points by which they were beaten in 2017 and 2019.
After missing the entirety of the Six Nations through injury, he brought electric pace and evasion to the backline. England looked to his pace, power and unpredictability as much as they could, feeding him on a dart off the blindside wing from one promising line-out.
On eight minutes, Australia's own indiscipline paved the way to the first England try. Feyi-Waboso was the swerving centre point of that early endeavour, a moment full of the intensity, intention and invention England have been desperate to show.
Borthwick will still have concerns. Centre Atkinson departed with a painful-looking leg injury in the second half, and Feyi-Waboso emerged at full-time in a protective boot.
Borthwick had made a fast start, along with tidying up discipline, a key aim for his side.
The body's language on the field showed mindset and intent, a sign that the team's pilot light was on and burning bright. As that energy spread to the stands, the vast majority of the 81,334 were won over by the display.
Feyi-Waboso, 23, made 113 metres from eight carries and beat seven defenders in 40 minutes of rugby. Those figures were unmatched by any other England player, even though he came off at the break and played only 32 minutes uninjured.