Gareth Batty led from the front with a superb 5 for 41 as Surrey thrashed Gloucestershire by 165 runs at the Kia Oval to avenge the defeat they suffered at the hands of the West Countrymen in last September's Royal London Cup final.
Surrey captain Batty ran through the middle and lower order with his offbreaks as Gloucestershire slid to 158 all out in reply to his side's challenging 50-over total of 323 for 8. The win lifts Surrey into third place in the South Group.
Batty and Jade Dernbach, who took 3 for 33, followed up half-centuries from Steven Davies, Rory Burns and Sam Curran in what was a thoroughly dominant Surrey team performance. Davies made 79 and Burns 50, but the icing on the cake in Surrey's innings was an 89-run stand between brothers Sam and Tom Curran. Sam Curran hit a List A career-best 57 from 56 balls, while Tom Curran was eventually run out off a wide for 39.
In reply, Gloucestershire never recovered from the early loss of Michael Klinger, Phil Mustard and Chris Dent to the pace bowling of Dernbach, who polished off the trio in the space of 11 balls. Only Hamish Marshall offered any resistance as the defending champions were bowled out in just 33.2 overs.
Jason Roy reacted to Surrey's decision to bat first by racing to 17 off his first nine balls, with four boundaries. But the visitors countered by having Aaron Finch lbw playing back to Matt Taylor and Roy edging Liam Norwell behind for 34 - low and to the right of keeper Mustard, who was making his debut for Gloucestershire on loan from Durham.
Davies lifted both Craig Miles and Benny Howell over midwicket for sixes on his way to a 47-ball half-century and added 77 in 12 overs with Dominic Sibley. But Howell struck when the latter, shaping to cut, chopped the ball on to his stumps for 27.
Left-hander Davies holed out to deep midwicket for 79 off Norwell, though not before Mustard had dropped a routine chance off the same bowler when he was on 75. Two overs later, Norwell added a third wicket to his tally when Ben Foakes was bowled through the gate.
Burns was caught behind shortly after completing a 49-ball fifty. But with the Curran brothers batting attractively and aggressively in their 13-over seventh-wicket stand, Surrey looked well placed at the halfway stage.
The Currans matched each other run for run, initially, but then Sam Curran took charge - pulling Taylor out of the ground for six and launching Tom Smith over long-off for another maximum. The 18-year-old eventually skied a pull to the wicketkeeper, though not before reaching his maiden one-day half-century, which came off 48 deliveries.
Gloucestershire's assault on a victory target of 324 could not have got off a worse start with Dernbach bowling both Klinger, who was undone by a cleverly disguised slower delivery, and Mustard, playing a loose drive, first ball. Two overs later, Dent responded by cutting Dernbach violently for four before getting a leading edge to cover point to make it 24 for 3.
Marshall's lone hand included a cut over third man for six off Stuart Meaker and a ramp shot off Tom Curran, which sailed over fine leg for another maximum.
Ian Cockbain, dancing down the wicket, edged Batty low to backward point and Graeme van Buuren was caught at short fine leg, though not before Marshall had moved to a 46-ball fifty. Howell was caught behind off a lifting ball from paceman Meaker, and when Marshall departed two overs later, caught behind off the same bowler for 55, it was all over bar the shouting.