Michael Klinger was joined by Chris Dent with the former driving Reed for four through the covers before Dent inside-edged Owen to the ropes at long-leg. A more orthodox cover drive for four saw Klinger take his side to the 50-mark in the ninth over. The Gloucestershire captain then lofted Owen over mid-wicket for four before Dent did the same for the day's first six. The left-handed also opted for the aerial route against Allenby as he struck successive balls for fours.
Dean Cosker's spin was introduced in the 14th over and he was harpooned for four over mid-wicket by Klinger but the bowler gained immediate revenge as the Australian chipped the next delivery straight into Wagg's grateful grasp at short extra cover. Alex Gidman duly joined Dent who added another four to his tally courtesy of a misfiled at long-on before lofted Cosker to long-off to bring up the 100 in the 16th over.
A single off Jones took Dent to his fifty from 39 balls - his first in the competition - and he celebrated by greeting the return of Wagg by steering him through backward point for four as Gloucestershire reached 120/2 at the halfway stage. After delivering a feisty maiden, Jones nearly dismissed Gidman who miscued an expansive blow just over the head of Cosker running back from point. He duly celebrated his good fortune by lofting North over the River Stand for six, before Will Bragg came on as the eighth bowler and claimed Gidman's scalp as he drilled Bragg to Owen at long-on.
141/3 saw Benny Howell join Dent who off-drove Bragg for four before edging him to third man. He then straight drove Reed for four and continued to work the ball around as North rotated his bowlers in a bid to stem the runs from the visiting batsmen who reached 185/3 after 30 overs. Dent went to his hundred in the grand manner by pulling Allenby for six having faced just 89 balls before lofting Cosker over extra cover for four. The spinner was then driven straight for six by Howell.
The batting powerplay was duly taken on 206/3 with Allenby and Wagg returning to bowl, and the latter ended the breezy stand as, with the total on 215, Howell was caught behind by Mark Wallace. James Fuller then joined Dent who scythed Wagg through extra cover for four, and swept Allenby to long-leg for another boundary. The next three balls disappeared for six, four and four as 21 came off the over.
Both batsmen then drilled Wagg straight for four as the powerplay yielded 49 runs before Fuller drilled Jones straight for four before holing out to Owen with the total on 260. Dent continued on to his 150, from 111 balls before Ian Cockbain swung lustily in the closing couple of overs as Gloucestershire ended on 288/5 with Dent ending on 151* - the fifth highest individual score against Glamorgan in the competition
Fuller then struck with his second delivery as Bragg departed lbw, before Chris Cooke struck David Payne for a brace of fours, but with the total on 22, Fuller struck again as he bowled Cooke. North then joined Wallace with the Club captain and one-day captain each looking to repair the early damage, and the pair each struck on-driven fours, but in the seventh over, North was run out by Howell as Glamorgan nosedived further to 27/3.
Allenby then joined Wallace and helped to stabilise things, initially with the series of one's and two's ended by a booming cover drive for four by Wallace as Glamorgan reached 50 in the 12th over. He continued to find the ropes as he twice swept Howell for four before pulling Payne for another boundary. Allenby also hoisted Ed Young into the Grandstand for six before Wallace reached his fifty by pulling Payne for six - his 50th delivery.
Allenby then steered Gidman for four behind square on the off-side but with the total on 122 he chipped Howell to Klinger at short extra-cover as Murray Goodwin became Wallace's new partner. He began with an on-driven four and another boundary to extra cover before Gidman fell heavily whilst fielding and departed with a shoulder injury. Young duly returned to the fray with Glamorgan needing 142 from the last sixteen overs, and after another series of scampered singles, Goodwin chipped Howell to deep square-leg for four before Wallace swept the seamer for four to bring up the fifty stand.
Goodwin then square drove Payne for four as the equation became 100 from the last ten overs, but next ball he miscued a straight drive into mid-off's hands. His departure saw Wagg join Wallace still with the powerplay to come. The pair scampered some furious singles before Wagg opened his shoulders against Payne with a straight six to bring up the 200. He followed it with another straight drive for four before hoisting both Young and Norwell over long-on for six as the equation became 60 off the last 36 balls.
At this point the powerplay was taken as Fuller returned to the attack at the Cathedral Road End with Wagg scything him through backward point for four as the fifty stand came up before Wallace reached his second one-day hundred for Glamorgan from 98 balls with a lofted off drive. 44 were needed from the last 24 balls as Wagg swatted Fuller over extra cover and through mid-off for a pair of savage fours as 31 were required from the last three overs.
Wagg then completed his fifty from just 26 balls as the equation became 25 from the last two overs. Wallace then posted his career-best score in one-day cricket by lofting Fuller to long-on for four but with the total on 271 and eight balls left Wagg was caught at long-on. Seventeen were needed off the final over - Wallace struck the first ball for two but failed to make contact with the next from Payne. The third was edged for four but the next three only yielded a trio of singles as Gloucestershire won by seven runs with Wallace unbeaten on a career-best 118.