Kent 210 for 4 (Billings 95*) beat Hampshire 207 for 6 (Dawson 75*, Denly 3-37) by three runs
Kent avenged last month's Royal London One-day Cup final defeat by securing a breathless three-run Vitality Blast T20 win over Hampshire in Beckenham.
For Sam Billings, his 95 from 54 balls, a T20 best, was a reaffirmation of his talent after long spells on the sidelines.
But it was Kent seamer Mitch Claydon who held his nerve at the death when, with six needed for a Hampshire win, a near-perfect yorker restricted the visitors to a single that sparked Kent celebrations for a third win in four starts.
Only a couple of days earlier, Claydon had been in the opposite position - on strike with six needed off the final ball, against Gloucestershire at Bristol, and again the bowler came out on top. This time he could celebrate the fact.
Claydon said: "You've just got to stay relaxed in a situation like that because you can go from hero to zero in the space of two balls. I've bowled a lot at the death throughout my career and I've come to terms with the fact that some days it comes off, others it doesn't.
"As long as your plans are right I'd back myself, but so many batsmen clear the fence so easily nowadays that I was only one boundary away from being a zero.
"What with my early season injury and my form since, I felt I owed the side something tonight and I'm really have to have delivered. I was initially going to bowl the penultimate over, but Sam wanted me to bowl the last to the biggest boundary. If we're under the pump at the end of the game I just tell Sam that I'll just bowl my best ball, and that's a straight yorker. I didn't have to think of anything else after that and thankfully I nailed it."
Hampshire, who have now lost their first three Vitality Blast games, made a disastrous start to their pursuit losing, James Vince, Colin Munro and Sam Northeast in the first seven balls.
Vince skied Denly to long-off to be caught by a galloping Carlos Brathwaite, Munro pulled a short one into the hands of square leg then, with his first ball of the game, Brathwaite produced a snorting lifter to have Northeast snaffled at slip for a first-ball duck at make it six for three.
Rilee Roussouw, Hampshire's Lord's century-maker and man-of-the-match, teamed up with fellow left-hander Tom Alsop to counter attack with a brace of sixes but Roussouw heaved at a Mitch Claydon slower ball to edge to Billings and leave Hampshire on 74 for four after the powerplay.
Alsop, who hit 72 in the Royal London 50-over final, maintained the high tempo by taking 12 off Imran Qayyum's first over of left-arm spin but, in attempting an audacious reverse lap he was bowled by Calum Haggett to go for 41.
Laim Dawson and Lewis McManus added a quickfire 55 in 5.3 overs before the latter sliced high to extra cover to go for 38 and give Denly figures of three for 37.
Dawson posted a 30-ball 50 but, in fading light and with 45 required from the last 24 balls, the pressure started to mount. Haggett and Brathwaite sent down a tight over, but Brathwaite leaked 14 in his final over to leave the visitors to score 16 off Claydon's last over.
Dawson chipped away with two more boundaries and with five needed off the final delivery, Claydon delivered a near perfect Yorker to limit Dawson, who finished unbeaten on 75, to a single.
Claydon led the Kentish celebrations with one for 33.but it had been Haggett's 3-0-18-1 that turned the tide Kent way.
Batting first after losing the toss, Kent posted 210 for four due, in large, to an unbeaten 95 from skipper Billings. The England ODI player hit seven fours and five sixes in his 54-ball stay that beat his previous T20 best of 78* scored for Pakistan Super League franchise Islamabad last February.
Home opener Joe Denly departed for 18 in the fifth when he skied a back-foot force against Chris Wood high to Dawson at long on to become Wood's 100th T20 victim. Then, in the next over, Heino Kuhn scooped a Ryan Stevenson slower ball to mid-on as Spitfires ended the powerplay on 50 for two.
After switching ends, Mujeeb Ur Rahman's second over proved considerably better costing only six, while Dawson continued to stem the flow of boundaries to restrict the hosts to 83 for two at their innings mid-point.
Billings marched accelerated with a six off Gareth Berg, who then conceded a no-ball free hit enabling Daniel Bell-Drummond to deposit another maximum over the ropes at long-on with 20 coming off the over.
Kent's third-wicket pair added 66 in 7.2 overs before Bell-Drummond, on 46, drove a low full-toss from Stevenson to James Vince at cover.
Billings slog-swept Wood for successive sixes to reach his 33-ball 50 with three sixes and as many fours. It was his 14th half-century in the format. Billings and Alex Blake posted the highest stand of the innings, adding 70 in five overs before Blake was run out by Wood's direct hit.
Carlos Brathwaite and Billings clubbed leg-side sixes in Gareth Berg's final over as Kent maintained a scoring rate in excess of 10 an over. Berg conceded 60 from his four wicketless overs and Ryan Stevenson bagged two for 39, but the wily Dawson proved the pick of their attack, conceding only 28 from his allocation.