In a low-scoring Hundred match only 220 runs were scored off the bat in 195 balls and 115 of them were made by Matt Short and Marcus Stoinis.
On a bowler-friendly surface both allrounders found it difficult with the ball, but with the bat the pair stood apart.
West Australian Stoinis made 55 off 39 balls as Southern Brave scrapped their way to 8-115. It did not look enough, but it would have been but for Victorian Short's unbeaten 60 off 41 balls.
"It's tough early here in Cardiff," said Short said. "Pretty spicy, some quick bowlers that get some nice bounce. A bit of a grind. Nice to bat second and get a bit of dew and skid off the wicket.
"Similar to most innings here: grind early, play good shots, hopefully the shine wears off and it gets a bit easier."
Put in to bat Brave found the medium pace seam and swing of Chris Woakes and Simon Cook almost unplayable.
Woakes took one for one off his first 10 balls with Ben McKinney caught behind for a two-ball duck. Cook had fellow opener Jamie Smith caught behind for a three-ball duck.
After 18 balls Brave had scored three runs for two wickets with Stoinis and Nikhil Chaudhary becalmed. At which point Stoinis decided there was no point in hanging around waiting to edge one and smacked Cook for successive off-side fours.
The muscular veteran hit two more fours off his next three balls, albeit one fortunate, and was off and running.
Fellow Australia international Chaudhary found it more difficult and eventually perished to a top-edge for 18 off 23. Wickets continued to tumble with only David Miller (21 off 17) also making double figures.
Stoinis continued as if playing a different game. He hit one six and eight fours before pulling his 39th ball to Lockie Ferguson on the backward square leg boundary.
Short was given the challenging task of the final set, his first of the match. It went six-wicket-six-wicket-single as Brave closed on 8-115. Woakes finished with 1-15 off 20 balls, Cook 3-14 off his 30.
Fire's innings was very similar with Short emulating Stoinis while wickets tumbled around him. He hit three of the first four balls bowled to him by Stoinis to the fence and put Adil Rashid into the stands.
He reached 50 by flip-ramping Jofra Archer to the fine leg boundary.
Only Joe Root (17 off 20) reached double figures until Tom Kohler-Cadmore (23 not out) provided belated support.
It fell to Stoinis to bowl the key penultimate set, with nine needed from 10. Short ramped his first ball to the boundary. That was effectively it, Fire winning with five balls left and Stoinis finishing with 0-30 off 20.
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