Gloucestershire 51 for 2 (Dent 28*) beat Glamorgan 45 for 1 by eight wickets
Glamorgan failed to take advantage of Essex's clash with Kent being a wash out as Gloucestershire claimed an eight-wicket victory in Cardiff.
With Essex stuck in the pavilion Glamorgan knew they could leapfrog them with a victory and progress to the quarter-finals of the Natwest T20 Blast but it was not to be.
The contest, which was reduced to five-overs per side, was instead a platform for a brilliant bowling display from Gloucestershire's attack as James Fuller bowled a maiden and Benny Howell conceded just one run from his over as they restricted Glamorgan to 45 for 1.
In reply, Chris Dent led the charge with an unbeaten 28 off 11 balls and Gloucestershire, who knew they could not be able to advance, reached a match-winning 51 for two with seven balls to spare.
Jacques Rudolph was quick to point out that they had been well beaten, but that there were positives to take from this year's T20 Blast.
"It was really disappointing. Gloucestershire outplayed us tonight and unfortunately we're out but I thought we had a fairly decent competition overall. Having said that, we've got a few lessons we can learn.''
Colin Ingram was sent out to open with Graham Wagg for the hosts and the South African left-hander got the innings off to a blistering start taking 17 runs off the first over.
While he was finding the middle of the bat Wagg played out a maiden over at the other end, the last ball of the second over hitting him on the helmet when he attempted a pull shot.
Ingram went for 18, caught in the deep by Dent off Kieran Noema-Barnett while Wagg continued to struggle to put bat on ball. He faced 12 dot balls in a Glamorgan innings that was only 30 deliveries long. His stay at the crease was ended when he was hit on the helmet for a second time, this one felling him and forcing him to retire.
Chris Cooke came out for the last four balls of the Glamorgan innings and he got them to 45 for 1 meaning Gloucestershire needed nine an over to win, a total that always looked far too small.
The Glamorgan bowlers managed to remove Gloucestershire danger man Michael Klinger in the second over. David Lloyd was the bowler and he collected his second wicket in the over when he bowled Geraint Jones for 10.
Glamorgan attempted to keep the run rate down, but having struggled with the bat and with Wagg unable to bowl following his blow when batting they never had enough runs to defend. Dent and Howell made light work of the total putting on 29 runs in just two overs to seal the win.
The result means that both teams are eliminated from the competition with the win not enough for Gloucestershire to go past Essex into a quarter-final spot.
When asked after the welfare of Wagg following his two blows to the head Rudolph said he seemed to be recovering but would be monitored closely. "He seems to be OK. We'll make a decision tomorrow to see if he's fit to play on Sunday,'' he added.