Glamorgan blew their chance to make the quarter-finals of the Friends Life t20 for the first time in four years after suffering a surprise nine-wicket hammering by Gloucestershire - a result which saw Durham assured of a place in the last eight.
Jim Allenby hit 85 not out for Glamorgan at Cardiff but without sustained assistance the hosts made just 141-5 from their 20 overs, which was comfortably knocked off by the visitors with Michael Klinger hitting 86 of their 145-1 with three-and-a-half overs to spare.
It was just a third win of the season for Gloucestershire, and with Glamorgan fluffing their lines, Durham were the big winners as they made the quarter-finals without having to lift a finger.
Allenby did his bit for Glamorgan, firstly sharing a 55-run opening stand with Marcus North until the Australian was bowled by Benny Howell for 20 at the start of the ninth over.
Only Murray Goodwin then got into double figures as batting partners came and went leaving Allenby to manfully fire his side up to a total that would be anywhere near a competitive one.
Allenby hit four sixes and six fours in his 58-ball innings of 85 but their 141-5 still looked a good few runs short.
And so it proved, with Glamorgan only able to get the one wicket in response - that being Chris Dent who was caught by Michael Hogan off the spin bowling of New Zealander Nathan McCullum for 25.
Dent's stand of 66 with Klinger came in just eight-and-a-half overs though and gave them a perfect platform to go on and claim a rare Twenty20 win for them.
Daniel Christian kept Klinger company with his 20-ball knock of 25, but the captain was the star of the show as he hit one six and 11 fours in his match-winning innings.