Surrey 183 for 2 (Sangakkara 81*, Stoneman 74) beat Glamorgan 239 (Ingram 72, Rudolph 57, Dernbach 3-30, S Curran 3-51) by eight wickets (DLS method)
The left-handed combination of Mark Stoneman and Kumar Sangakkara guided Surrey to a comfortable first victory in the competition this season as the visitors easily chased down the amended target of 182 in 29 overs in Cardiff.
After Dominic Sibley was out in the fourth over, the second wicket pair put on 125 in rapid time with Stoneman scoring 74 from 48 balls, with a high proportion of his runs - 56 - coming in boundaries.
The Glamorgan bowlers struggled with a wet ball, as the sparse crowd were treated to a masterclass from the Sri Lankan batsman, who was undefeated on 81 with eleven fours as Surrey won with five overs remaining.
Surrey, who won the toss and on a green tinged pitch and an unfavourable weather forecast, chose to field first. Gareth Batty's decision was immediately vindicated when Jade Dernbach trapped David Lloyd with the third ball of the innings, and two overs later knocked back Kiran Carlson's off stump.
Jacques Rudolph and Colin Ingram then resurrected the Glamorgan innings with some positive strokeplay, with Ingram striking Ravi Rampaul for one of the biggest sixes seen on the ground, a massive blow that landed some 150 yards away over backward square leg.
Rudolph, no less effective, followed up the 121 he scored against Gloucestershire in the opening game, by scoring 57 from 65 balls, with nine fours, before he was bowled off the inside-edge by Sam Curran.
Ingram, who before the game was awarded his county cap, struck two other sixes and four fours in his 72, made from 96 balls, before he was caught on the long-on boundary attempting another maximum.
After the third-wicket pair had added 113 in 20.2 overs, Surrey's attack assumed control, with Dernbach rewarded for bowling a full length in his opening overs, then restricting Glamorgan's progress towards the end of the innings with his back-of-the-hand slower deliveries.
Batty also bowled a miserly spell, with figures of 10-1-36-1, and with Glamorgan's late-order batsmen finding various ways of getting out - caught off the back of the bat and a comical run out - the home team were dismissed for 239 with nine balls of their innings remaining.