Kent 138 for 3 (Bell-Drummond 56*, Cox 31*) beat Gloucestershire 137 (Hammond 30, Leaning 2-16) by seven wickets
Gloucestershire started well enough, advancing to 51 for 1 thanks to a brisk 30 from Miles Hammond, only to then lose nine wickets for 86 runs in a collapse which culminated in them being dismissed for a wholly inadequate 137 in 19.3 overs.
Seamers Michael Hogan, Kane Richardson and Grant Stewart each claimed two wickets apiece, while off spinner Jack Leaning returned figures of 2 for 16 from four overs as Kent produced a coherent performance in the field, fully justifying the decision to bowl first.
Gloucestershire have now lost five of their eight matches in this format and only victory over fourth-placed Hampshire in Bristol on Tuesday will suffice to keep alive their outside hopes of making the knockout stages. Although Kent have now won three successive games, they also trail Hampshire by four points and have much ground to make up if they are to stage a late challenge.
Put in to bat, Gloucestershire made the worst possible start, Grant Roelofsen pushing at the first ball of the innings, sent down by Fred Klaassen, and feathering a catch to Jack Leaning at slip. Apparently unperturbed by such an early setback, Hammond and Ben Wells set about redressing the balance in a hard-hitting second-wicket alliance of 51 in five overs.
But Kent quickly regained a stranglehold, Richardson claiming two wickets in the space of three deliveries in the sixth over to nip any sustained recovery in the bud. He clean bowled a swinging Ben Wells for a run-a-ball 15 and then induced new batter Ben Charlesworth to chance his arm and hole out to Tuwanda Muyeye at deep square leg without scoring as the home side completed the powerplay on 57 for 3.
Gloucestershire's plight deepened in the next over, Ollie Price risking a quick single against Stewart and being run out for five by Cox's rapid pick-up-and-throw from mid-on, while Hammond fell in the eighth, caught at the wicket by Sam Billings off the bowling of off spinner Leaning.
Gloucestershire's new captain had raised 30 from 20 balls, with five fours and a six, and at the point of his departure, the hosts were 64 for 5, having surrendered four wickets in just 15 balls.
Leaning struck again in the tenth, Graeme van Buuren hoisting him straight to Cox at long-off as Gloucestershire further subsided to 73 for 6 at the halfway stage. Slow left armer George Linde then conceded just 15 runs in 18 balls from the Bristol Pavilion End as Tom Price and Zafar, charged with the not inconsiderable task of rebuilding, were effectively frustrated by spin during the crucial middle overs.
Demonstrating necessary urgency under duress, Zafar hit Leaning back down the ground for six in the 14th over in a quest to re-ignite an innings which had lost it's way, while Tom Price was dropped on nine by Hogan at short fine leg off the bowling of Klaassen, a lapse that suggested a Gloucestershire recovery was still possible.
But the returning Hogan ended any chance of that, persuading Zafar to hole out to long-off for a 20-ball 25 and then removing Matt Taylor in identical fashion four balls later. Tom Price skied Stewart to Billings and departed for 11, but Payne smashed 16 off nine balls in a last-wicket stand of 23 with Smith, to at least give home supporters a glimmer of hope.
Further hope was forthcoming as Payne ran out Muyeye off his own bowling in the first over to subject the Kent reply to early pressure. When Tom Price held a smart return catch to dismiss Joe Denly for 11 and claim his maiden T20 wicket, the visitors were 38 for 2 in the sixth over and Gloucestershire's players were prepared to believe.
Captain Billings provided a necessary change of gear, plundering 15 runs from one Ollie Price over to set a tempo which quickly saw him catch up Bell-Drummond and advance the score to 75 for 2 at the end of 10 overs.
By the time Wells ran out Billings for an 18-ball 28 to terminate a third-wicket alliance of 39, the rate was almost down to a run a ball and Kent, with Bell-Drummond set, were handily placed.
Cox picked up where Billings had left off and Hammond recalled the experienced Payne to bowl the fifteenth in a last-ditch attempt to turn the tide. But Cox helped himself to 10 runs off the over and Bell-Drummond went to 50 via 46 balls as Kent closed inexorably on their target.
Having played his part superbly well, Cox finished on 31 not out from 20 balls, while Bell-Drummond weighed in with a quartet of fours and a brace of sixes in an extremely well-paced innings.