Will Jacks cracked a match-winning 81 as Oval Invincibles picked up their first win of the season and inflicted a second defeat on Welsh Fire.
Jacks hit four sixes and five fours in his 45-ball innings as Invincibles battled up to 158-5 on a tricky pitch in Cardiff.
Fire started well in their chase with Joe Clarke hitting early back-to-back sixes but they then lost regular wickets throughout, finishing on 119-6, to lose by 39 runs.
Here’s what also happened:
- Jason Roy's summer of struggles continued as the England opener was caught at short fine leg for just 10. But, former England batter Kevin Pietersen says people need to "leave Roy" alone and England should stick with him ahead of October's World Cup in Australia.
- Will Jacks patiently built his innings, scoring 21 from his first 18 balls, before increasing the pace and clearing the boundary with frequency as the innings developed.
- Tom Curran removed Clarke, who made 37 from 29 balls, and the dangerous South African David Miller. He also bowled the first maiden of this year's tournament and finished with 2-14
- West Indies spinner Sunil Narine was the pick of the Invincibles bowlers, dismissing Tom Banton, England Test batter Ollie Pope and Fire captain Josh Cobb, to finish with figures of 3-21.
Speaking about Jacks, Invincibles captain Sam Billings said: "His season goes better and better - he is a young player with hugely exciting potential.
"That was a coming of age knock, we know how destructive he can be but that was seriously mature."
Oval Invincibles are next in action against Northern Superchargers on Thursday at the Kia Oval. That game will start at 15:00 BST with the women's competition starting with the same fixture later that evening.
Welsh Fire now have six days off and will host last year's runners-up Birmingham Phoenix in their next Saturday.