Bracewell, who represented New Zealand at under-19 level, came to the crease at No 3 as Wellington fell to 24-4 in their chase. He then proceeded to lay into the Stags' attack, including hitting three sixes in a row off the bowling of cousin and former Black Caps seamer Doug Bracewell.
The Wellington skipper's big hitting saw his side eventually need 17 runs from the final over to pull off an unlikely victory, one that became much more possible when he hit the first ball from Tom Bruce for six.
Left requiring 10 runs from the last three balls, Bracewell promptly smacked a six and a four to set off wild scenes of celebration as his Firebirds teammates stormed the field.
Bracewell attempted to play down his historic knock soon after the game, telling Spark Sport with a straight face that it took a "team effort" to record the phenomenal win.
"Coming in, we knew it was going to be a good wicket, and CD certainly showed that with the bat," he said. "We kept losing wickets at the top and through the middle, so we just tried to take the game deep, and it's amazing what happens when you just believe.
"You're always looking to go out there and just play positive, and it's a really conducive runscoring field out there today â fast outfield and short boundaries â so we kept up with the rate. And you've just got to try back yourself and take runs at the back end."