Gloucestershire 168 for 7 (Klinger 48, Rawlins 2-19) beat Sussex 163 for 8 (Rawlins 69) by three wickets
Graeme van Buuren hit the final ball of the match for six as Gloucestershire squeezed past Sussex by three wickets to secure a home tie in the quarter-finals of the Vitality Blast. Needing six off the final over, Gloucestershire were restricted to four runs off the first five balls by Reece Topley, but van Buuren smashed the last delivery over the longest boundary on the ground at deep midwicket to finish unbeaten on 37 from 20 balls.
Gloucestershire looked to have a chase of 164 under control when captain Michael Klinger, fresh from Thursday's unbeaten hundred against Kent, was helping take his side to 103 for 2 in the 13th over. But Klinger was caught behind off left-arm spinner Delray Rawlins and in his next over Rawlins, who had earlier top scored with 69 in Sussex's 163 for 8, bowled Ryan Higgins for a duck.
With Will Beer picking up Jack Taylor for a single, Gloucestershire were 115 for 5 and needed 48 off the last five overs. Ian Cockbain got them closer with 37 off 25 balls before he was caught at long-on in the 18th over.
Gloucestershire took 12 off the penultimate over from Chris Jordan but Topley appeared to have given Sussex a chance until van Buuren swung with mighty effect off the last ball. It was Sussex's second successive defeat at Hove, but they had already secured home advantage in next week's quarter-finals.
Sussex had earlier made 163 for 8 after being put in, a slightly disappointing outcome after they had reached 111 for 2 in the 12th over thanks to a stand of 108 from 60 balls between Luke Wright and Rawlins. They came together in the second over after the hosts had lost Phil Salt and Laurie Evans, who was run out by Miles Hammond's direct hit from backward point after hesitating slightly in backing up Wright's call for a single.
Left-hander Rawlins had a reprieve when Tom Smith dropped a straightforward chance at point off van Buuren when he had scored just a single. He made the most of his fortune, using his strong wrists to whip the ball into the gaps and matching his captain when it came to the big hits as well.
They took 20 off Josh Shaw's first over and it was a surprise when Wright heaved across the line at the former Yorkshire paceman and lost his leg stump for 41. Rawlins fell for 69 when he was caught and bowled off a high full toss from Andrew Tye in the 14th over, having hit eight fours and two sixes in 41 balls faced.
Sussex could only score 43 in the remaining six overs as wickets fell regularly. David Wiese made 26 but the outstanding Andrew Tye conceded just 11 runs in his four overs and David Payne backed him up with 3 for 36 including the wickets of Wiese and Ollie Robinson in his final over.