Surrey 296 for 6 (Sibley 105, Patel 72, Geddes 61) beat Leicestershire 279 (Budinger 70, Scriven 55, Steel 3-48) by 17 runs
In-form Dom Sibley's second hundred in three matches spurred Surrey to end a run of five straight defeats with their first Metro Bank One-Day Cup victory of the season, dealing a blow to Leicestershire's hopes of qualifying for the knock-out stages.
Sibley followed his 149 against Warwickshire and 72 versus Nottinghamshire with 105, sharing stands of 138 for the first wicket with Ryan Patel (72) and 111 for the second with Ben Geddes (61) as Surrey totalled 296 for 6. It proved enough despite losing five wickets in the last eight overs.
The Foxes were given a chance as opener Sol Budinger maintained his place as the competition's leading run scorer by hitting 70 from 68 balls and Tom Scriven's career-best 55 raised hopes of a gripping finish for a crowd of almost 1,400 but ultimately proved in vain, leg-spinner Cameron Steel taking 3 for 48 for the victors.
All-rounders Ian Holland, with 2 for 50, and Scriven, with 2 for 51, were the pick of the Foxes bowlers, with 19-year-old seamer Sam Wood taking 1 for 34 on his List A debut.
If the Foxes finished well with the ball, the start provided by Sibley and Patel with the bat was comfortably Surrey's best of the season.
Asked to bat first on an overcast morning, Surrey were 51 without loss from 10 overs and were 125 for nothing by halfway, Sibley having gone to fifty from 59 balls with Patel reaching his from 72.
Patel suffered an unlucky dismissal. Shaping to hook the tall Wood, he seemed to be hit on the shoulder before the ball deflected off his helmet on to the stumps.
Geddes maintained Surrey's positive start. Dropped by Chris Wright at fine leg on 35 off Liam Trevaskis, he cashed in to the tune of 26 more runs before falling to a catch at deep midwicket off Roman Walker.
Sibley had gone to his hundred from 115 balls in the 42nd over with his 11th four but soon miscued to long-off, giving Scriven wickets in consecutive overs after Rory Burns was bowled sweeping.
Holland then had Josh Blake caught at backward point and 19-year-old Surrey debutant Ollie Sykes at long-on, a fifth wicket to fall in seven overs with Surrey slipping from 249 for 1 to 286 to 6.
The Foxes' chase suffered a double stumble to leave them 49 for 2 from 10 after Holland picked out deep backward square off James Taylor and Lewis Hill was caught behind off Conor McKerr.
Ajinkya Rahane had an escape when he was spilled at cover on four off McKerr, which was beginning to look like an expensive drop by Steel as he and Budinger began to accelerate, the latter passing fifty for the fourth time in five innings, the run including 120 against Essex at Chelmsford. But Rahane could make only 27 before he was caught at midwicket off Patel, the ball perhaps sticking in the pitch a little.
Budinger and Peter Handscomb shared a match-winning 113-run partnership against Essex on this ground last year but could add only 48 this time before Budinger holed out to deep midwicket.
It felt like a significant moment at 142 for 4 in the 26th, one that was amplified two overs later as Handscomb hit straight to cover, both batters falling to Steel.
Trevaskis was bowled by left-arm spinner Yousef Majid and Cox fell leg-before to McKerr. Scriven's 45-run eighth-wicket stand with Wood, stumped off Steel for 22, kept the contest alive, Scriven hitting two sixes, but 20 off Taylor in the last over was always unlikely and the match ended with Scriven falling to a stunning catch by Patel at backward point as Leicestershire were all out for 279.
With three wins from five, qualification for the knock-out stages is still possible, although Group B leaders Warwickshire and Glamorgan both have five wins from five.
Both sides wore black armbands and a minute's silence was observed at the start of the match as the cricket world mourns the loss of great England and Surrey servant Graham Thorpe.