Durham 275 for 5 (Smith 120*, Muchall 52*) beat Surrey 142 (Breese 4-33, Borthwick 3-41) by 133 runs
An extraordinary onslaught by Will Smith propelled Durham to a 133-run victory in their final Yorkshire Bank 40 match and ended a miserable five days for Surrey at Chester-le-Street.
Beaten by an innings and 144 runs in the County Championship, Surrey fielded a young side and would have been happy to have Durham struggling on 112 for 5 in the 23rd over.
But Smith's unbeaten 120 took them to 275 for five, in partnership with Gordon Muchall (52 not out), the former captain reaching 50 off 52 deliveries, 100 off 73 and facing 79 balls in total. He thrashed five sixes and 10 fours, most of the boundaries coming as the pair took 101 off the last seven overs.
Smith's only previous one-day century was 103 in a 50-over match at home to Worcestershire in 2007 and he has not been a limited-overs regular in recent years.
Gareth Breese and Scott Borthwick then took centre stage, sharing seven wickets, as Surrey were dismissed for 142 in 30.5 overs.
Neither side could qualify for the semi-finals, with Durham's chances ending on a poor pitch at Derby earlier this month, which resulted in the hosts suffering a two-point penalty.
Among Surrey's youngsters was George Edwards, who looked lively with the new ball, having Phil Mustard caught at second slip for a duck. Tom Curran, son of the late Kevin Curran, also impressed, clean bowling Ben Stokes for six.
But when Edwards returned during the batting Powerplay he conceded 18 off the 36th over, while the experienced duo of Tim Linley and Zander de Bruyn also came under heavy fire.
It was all the more remarkable because Durham's innings had stagnated after acting captain Mark Stoneman opened up with 31 off 25 balls. The only boundary between the 17th and 30th overs resulted from a misfield at deep midwicket.
Left-arm spinner Zafar Ansari conceded only 16 in his first five overs, but 20 came off his next two as the floodgates opened. Muchall matched Smith in reaching 50 off 52 balls, but was content to let his partner have the strike in the last few overs and remained unbeaten on 52.
Ansari and 17-year-old Dominic Sibley tried to hold the Surrey innings together after veterans Vikram Solanki and De Bruyn surrendered tamely to Borthwick to leave the visitors toiling on 68 for four following the early losses of openers Arun Harinath and Jason Roy.
Sibley made 37 before chipping Gareth Breese to wide mid-on and Ansari scored 33 before driving Breese to long-off as Surrey subsided for 142 in 30.5 overs.