Gloucestershire 165 for 4 (Klinger 58, Hammond 36) beat Middlesex 160 for 7 by six wickets
Michael Klinger's assured half-century saw Gloucestershire resume their T20 hoodoo over Middlesex with a comfortable six-wicket win at Uxbridge.
Gloucestershire's first defeat to Middlesex at Uxbridge last season came at the 12th attempt but thanks to Klinger's 58 that result proved the exception.
The 38-year-old Australian was content to play second fiddle initially to Miles Hammond before taking responsibility for seeing his charges comfortably to their under-par target with a succession of elegant variations.
For Middlesex, the only cause for cheer was a belligerent 33 in just 12 balls from James Fuller, back playing again after an 18-month injury hell.
Middlesex were glad to have skipper Dawid Malan back from 12th-man duties with England, but the left-hander's recent run of low scores continued as he chipped one back to David Payne in the first over to depart without scoring.
Worse followed in the next over when Paul Stirling skied a top-edge from Matt Taylor which eventually came down into the gloves of wicketkeeper Gareth Roderick.
Nick Gubbins responded with four quick-fire boundaries but when he edged Thisara Perera to Roderick, Middlesex were 35 for 3.
Attempts at a rebuild by Stevie Eskinazi and John Simpson also came up short when the latter holed out at long-off for 13 off Benny Howell. It was all-rounder's last contribution to the bowling effort as he pulled up injured one ball later and promptly left the field. He has damaged a groin and could miss several weeks - a blow for Gloucestershire as he is the kingpin of their attack.
However, there was to be no respite for Middlesex as Ryan Higgins grabbed the chance to bowl against his former county and promptly had Eskinazi caught off the glove.
At 63 for 5 off nine, Middlesex effected a rally of sorts courtesy of Dwayne Bravo and Hilton Cartwright, the pair adding 47 in seven overs before Cartwright failed to clear cow corner.
Such was the Gloucestershire strangled-hold, typified by Middlesex old-boy Tom Smith's four overs for just 15 runs, it was the 18th over before Bravo (34) flayed the first six of the innings. He would depart next ball, hit wicket, to cue Fuller's extraordinary cameo.
Gloucester began their pursuit of 161 at full throttle, Hammond, in only his second match in almost three years because of architectural studies, hammering eight fours in a breezy 36 before hitting a Bravo full toss straight to substitute fielder James Harris.
Under no scoreboard pressure skipper Klinger and Ian Cockbain continued, albeit with few boundaries, to tick the score along until the latter lofted Stirling to Cartwright on the square leg boundary with the score on 93.
Roderick weighed in with 24 to go with his three catches and although Klinger, too, left before the end, bowled by Bravo, Gloucester eased home with eight balls to spare.