A fighting 96 at Headingley from Gloucestershire Gladiators' Australian captain, Michael Klinger, condemned Yorkshire Vikings to yet another defeat in the Yorkshire Bank 40 and maintained his own side's place at the top of Group C.
Once again, Yorkshire's depleted one-day attack was unable to put their opponents under sufficient pressure as they chased a 241-run target, achieved with five wickets and 11 balls to spare.
With Tim Bresnan playing for England, Liam Plunkett and Jack Brooks injured and Ryan Sidebottom and Steven Patterson rested, teenage seamer Ben Coad was given a first-team debut and he deservedly picked up the important wicket of Hamish Marshall.
Marshall and Klinger shared an opening stand of 74 in 12 overs, the former setting the tone by driving Moin Ashraf over long-off for six.
Coad gave away only one run in a tight first over and went on to dismiss Marshall for 44, thanks to a great diving catch at short fine-leg by Iain Wardlaw.
But Klinger then found a more-than-capable partner in wicketkeeper Gareth Roderick, who came to the crease in place of Chris Dent, the latter having left the field with a side injury during the Yorkshire innings.
Gary Ballance just failed to hold on to a stinging chance at short cover from Klinger before the batsman drove Richard Pyrah for sixes either side of completing a fifty from 57 balls. Roderick also cleared the rope off Adil Rashid on the way to his own half-century from 55 deliveries.
The stand had galloped on to 119 in 19 overs when Roderick tried to steer Wardlaw over the slip area and was caught behind for 63 from 66 balls with four fours and a six.
Alex Gidman saw his middle stump knocked back by Pyrah, who also had Benny Howell driving a high catch to Coad at mid-on, and Klinger robbed himself of a century by hitting Ashraf to Ballance at mid-off, his 96 coming off 98 deliveries with six fours and three sixes.
That left Gloucestershire on 226 for five in the 37th over but they were still very much in charge and Ian Cockbain and James Fuller saw them safely home.
Yorkshire had reason to feel disappointed with their score of 240 for six after winning the toss on a good batting pitch as too many batsmen got out to poor shots when looking well set.
The backbone to the innings was provided by Phil Jaques, who survived a difficult chance to Gidman at slip before he had scored and went on to make 70 off 86 balls with seven boundaries.
Rashid contributed an unbeaten 43 from 30 deliveries and has not been dismissed in any of his last four innings in all competitions, boasting an average of 254.50 in the LV= County Championship and 81.50 in the YB40.
The experiment of Pyrah opening the innings with skipper Andrew Gale failed once again, the former tamely driving Graeme McCarter low to Howell at cover in the second over to leave the right-hander with only 29 runs from five knocks.
Gidman put down Jaques as he dived to his right and there was another fortunate moment for the Australian left-hander when he top-edged Fuller just out of 17-year-old debutant Miles Hammond's reach at midwicket.
Gale added 52 with Jaques but, after striking 26 off 28 balls, attempted an ungainly pull outside off-stump and presented Gidman with an easy catch at midwicket.
Ballance joined Jaques in a third-wicket partnership of 63, the highest of the innings, though the former survived a two-handed slip chance to Marshall and then a fierce on-drive to Gidman.
Off-spinner Hammond bowled much better than his final figures of 1-50 would suggest, his sole victim being Ballance when he holed out to Dent at deep backward square-leg.
Jaques completed a half-century off 66 deliveries with five boundaries while Adam Lyth advanced to 30 with some stylish shots until he went back to cut at Gidman and was bowled.
Yorkshire were 164 for four in 30 overs and next to go was Jaques, who moved well outside off stump in a bid to paddle Gidman and was bowled.
Andrew Hodd drove at David Payne and was caught at slip by Klinger and it took an unbroken stand of 52 in seven overs between Rashid and Will Rhodes to give the score a reasonable look.