With just under five minutes left in a level game, the penalty was close enough to the touchline to make it risky, but close enough to full-time to make it tempting.
Before many of those watching on TV or at the Aviva Stadium had processed the risk and reward, Ross Byrne had pointed for the posts and called for the tee.
"Ross came straight up to me with a little smile on his face, and I knew that was a good sign," said James Ryan, who filled in as captain in the final 30 minutes of Saturday's 13-10 win against Australia.
"He had unbelievable confidence, unbelievable bottle to come in late and be 24th man and come onto the bench and then into the game and kick the winning penalty.
"It was brilliant."
Byrne's strike floated straight between the posts, enough to see Ireland hold out for victory, and cap off a remarkable week for the Leinster out-half.
Twenty one months since his last Irish cap, Byrne (below) had been called into camp on Monday afternoon after training with his province that day. Initially brought in as emergency cover, he was promoted to the bench shortly before kickoff on Saturday evening after Johnny Sexton tweaked his calf.
Having come on for Jack Crowley with eight minutes to play, he made himself the hero with the game-winning kick, a deserving moment for a player who has often been thrown into the most unforgiving situations in his previous 13 caps.
It was a tough kick, close to the right touchline, and had he missed, the scrutiny would likely have fallen on Ryan rather than Byrne, for pointing at the posts rather than the corner.
The stand-in captain experienced the fickleness of hindsight earlier this year when Ireland were beaten 30-24 by France in Paris, with his decision to kick a late penalty rather than
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