Hampshire 229 for 6 (Taylor 54*, Berg 52*) beat Glamorgan 227 (Ingram 64, Crane 4-46, Berg 3-46) by four wickets
An unbeaten partnership of 85 between 21 year-old Brad Taylor and Gareth Berg enabled Hampshire to win by four wickets and also secure their place in the knockout stages of the competition.
They required 228 to win after Glamorgan had underachieved in their innings. Although Hampshire faltered in mid-innings, the unbroken seventh wicket partnership guided them safely to their target with 6.4 overs to spare.
Glamorgan, who were put in on a slow St Helen's pitch, made a steady start, with Nick Selman and Aneurin Donald putting on 48 in eleven overs before Donald pulled a short ball to mid-wicket in Gareth Berg's first over.
Mason Crane was on in the eleventh over, and took wickets in his fourth and sixth overs. Selman nicked one to the wicketkeeper, then Kiran Carlson was caught at backward point.
David Lloyd was also dismissed by Berg and after their promising start, the home team had lost four wickets for 45 runs.
Colin Ingram and Graham Wagg then repaired the early damage, with some sensible shot selection, with Ingram reaching his third half-century in this year's competition.
After the sixth wicket pair had put on 56, Ingram was unlucky to be caught on the mid-wicket boundary off a long hop from Crane, who then took his fourth wicket when Andrew Salter - four balls later - tapped a full-toss back to the bowler.
Crane ended with 4 for 60 from his 10 overs, but the England spinner was rather fortunate, with his victims guilty of some reckless shot selection.
After Wagg was caught on the long-off boundary, the tail wagged as Lukas Carey and Timm van der Gugten put on 30 runs before Glamorgan were all out with eight balls remaining.
Needing to score at the relatively modest rate of four and a half an over, Hampshire lost Rilee Rossouw in Timm van der Gugten's second over, with Donald holding on to a steepler on the mid-wicket boundary.
James Vince soon made his intentions clear, by advancing down the pitch to Carey, striking him for two straight boundaries, and when Ruaidhri Smith replaced Carey, he was punished for three fours in his first two overs.
Van der Gugten then claimed his second wicket when Tom Alsop struck a short ball to mid-wicket, where Selman held on to a low one-handed catch. Vince continued to attack but after scoring 41 from 38 balls, with six fours, he was leg before attempting to turn Salter's off-spin to the on-side.
After Jimmy Adams chopped on, and Joe Weatherley was caught behind from Wagg's first ball, Hampshire had stumbled, and when Lewis McManus was also caught by the wicketkeeper, the visitors were in some trouble at 144 for 6.
Much depended on the seventh wicket pair and they duly responded by playing watchfully at the start, before accelerating towards the end of the run chase. Taylor top scored with an unbeaten 54 and with Berg also reaching a half-century, the two all-rounders also shared six wickets to produce matchwinning performances.