Gloucestershire 269 for 3 (Wells 108*, O Price 85*) beat Durham 267 (Bedingham 64, Borthwick 57, Anwar 3-38) by seven wickets

Called into the side just minutes before the scheduled start of play as a replacement for Graeme van Buuren, who hurt himself in the warm-up, Wells top-scored with a hard-hitting career-best 108 not out from 76 balls as Gloucestershire chased down a target of 268 with 13.3 overs to spare to progress to the knockout stages.

In-form Price finished unbeaten on 85 off 103 balls with 11 fours and James Bracey smashed a quickfire half century for Gloucestershire, who made 269 for 3 and will now face Lancashire in a home quarter-final tie at Bristol on Friday.

Scott Borthwick and David Bedingham posted 57 and 64 respectively, while Liam Trevaskis contributed 41 as Durham made 267 for 9 in their 50 overs. But veteran spinner Tom Smith removed Bedingham and bowled well during the middle overs to return figures of 1 for 37 from 10 overs, while Anwar Ali claimed 3 for 38 to keep Durham in check.

Arriving in the middle with Gloucestershire's reply poised at 85 for 3, Wells then stole the show with his bold stroke-play. His performance was all the more remarkable given that he had limped off during the early stages of the Durham innings, clutching a hamstring that continued to trouble him throughout the first half of the match.

Having won five of their previous seven group games, the home side oozed confidence thanks to the excellent start afforded their reply by Bracey. In supremely confident mood after scoring a career-best 224 not out against Somerset on his last appearance at Bristol, Gloucestershire's captain picked up where he left off, timing the ball superbly to raise a half century in just 38 balls. Yet his innings ought to have been terminated on 25, Brendon Glover dropping the former England man on the fine leg boundary off the bowling of Jonathan Bushnell.

Bracey certainly made good his escape, moving to 50 with his fifth maximum, hoisted over deep backward square at the expense of Oliver Gibson. Much to his annoyance, he then suffered a loss of concentration and dragged a wide delivery from Glover onto his stumps, having dominated a whirlwind partnership of 73 in 12 overs with Price. When new batsman Miles Hammond was bowled by slow left armer Liam Trevaskis six balls later, Gloucestershire were 85 for 3 in the sixteenth over, their innings in need of a re-set.

Wells provided the perfect response, going on the attack from the outset to reclaim the initiative for Gloucestershire, the fourth wicket pair raising 50 from 36 balls. Moving better than at any stage when in the field, Wells mustered a display of clean hitting to rival that of Bracey, the Academy product going to a 36-ball 50 via his ninth four.

Gloucestershire's rock, Price set his sights on batting through, reaching a chanceless 50 in 69 balls as the home side advanced their score to 152-3 at the halfway stage, requiring a further 116 runs at 4.22 an over. That proved comfortably within the grasp of the fourth wicket pair, whose alliance realised three figures from 79 balls, 66 of those runs coming by way of boundaries.

Happy to see off dangerman Migael Pretorius, who removed Chris Dent in his first spell, Price and Wells took apart the rest of the bowling as they engaged in their own personal race to reach a hundred. Wells won that particular battle, pulling Trevaskis for his 14th four to post his maiden List-A century from 72 balls. He also hit 4 sixes as 80 of those hundred runs came in the form of boundaries.

Believing a used pitch would become progressively more difficult to bat on as the day progressed, Alex Lees asked Gloucestershire to field and must have been well satisfied when his side reached 152 for 2 inside 28 overs.

Zaman Akhter removed Michael Jones cheaply and Paul van Meekeren had Lees caught at deep backward point for 22 as Gloucestershire took advantage of a slow pitch and uneven bounce to reduce Durham to 50-2 inside 11 overs. But Borthwick and Bedingham then launched a concerted recovery, applying themselves sensibly in a third wicket alliance of 102 in 17 overs, which served to put the visitors on top.

Scoring freely on both sides of the wicket, Borthwick was first to 50, the left-hander going to that landmark via 60 balls with 6 fours as Durham assumed a position of strength. Adept at finding gaps in the field, Bedingham faced just 49 balls in raising his third half century in seven innings in the 50-over competition this summer, clipping Josh Shaw behind square for his second four.

Gloucestershire's bowlers appeared to be at a loss as to how to part the third wicket pair and van Meekeren found the going especially challenging, sending down four no balls and three wides as his first eight overs cost 64 runs.

Relief arrived in the form of an unexpectedly loose shot from Borthwick, who drove Tom Smith uppishly to Akhter at long-on and departed for a 77-ball 57. His dismissal proved a seminal moment, slow left armer Smith and seamer Shaw conjuring 15 dot balls in the next 26 deliveries to build pressure.

Eager to break the stranglehold, Bushnell pushed a ball from van Meekeren to mid-on and attempted a risky single, only to be superbly run out by Price's direct hit. Durham were further undermined by poor decision making three overs later, Chris Dent running out Bedingham for 64 after the South African had hesitated when called through for a single by Trevaskis. Bedingham had faced 71 balls, accrued 2 sixes and 2 fours and, with him, went Durham's last opportunity to post a truly imposing total.

Trevaskis did his best to atone, scoring 41 from 43 balls and dominating a stand of 56 in 9.1 overs with Tomas Mackintosh, before holing out to backward point and becoming the first in a trio of batsmen to succumb to experienced former Pakistani international Anwar, who finished with 3-38 in eight overs to keep Durham in check at the death. Mackintosh contributed 29 from 31 balls before falling to van Meekeren, but there was a feeling that the visitors had under-achieved after building such a promising early platform.