Warwickshire 284 for 5 (Bell 98, Trott 70, Rafiq 3-35) beat Yorkshire 281 (Root 83, Waite 71, Bresnan 65) by five wickets
Bottom-of-the-table Warwickshire turned the Royal London Cup North Group table on its head with a five-wicket win over Yorkshire at Edgbaston.
The Bears' defence of the trophy was already over after six successive defeats while The White Rose went into the match top of the group. Yorkshire will still qualify but have ceded top spot in the group to Worcestershire, who defeated Durham at New Road.
They built a meaty total thanks to Joe Root's stylish 83 and a muscular sixth-wicket stand of 116 in 15.1 overs by Tim Bresnan and Matthew Waite, who struck a a List A-best 71 from 58 balls.
Warwickshire's reply was robustly launched by Jonathan Trott and Sam Hain. And after a wobble induced by spinner Azeem Rafiq, they were steered to victory by a cleanly-hit alliance of 111 in 106 balls between Ian Bell, who made 98 from 85 balls, and Rikki Clarke.
Warwickshire spinner Jeetan Patel said: "We have come off a run of a few really bad losses and some that were quite tight but credit to the guys for the way they came out today. Grant Thornton bowled really well which is where we need to get to. We are an ageing teams with a lot of experience but we need to be able to trust the younger guys."
After choosing to bat, Yorkshire lost Adam Lyth to the first ball of the match, from Keith Barker, which he edged to wicketkeeper Tim Ambrose.
Jonny Bairstow soon miscued Rikki Clarke to mid-on and Peter Handscomb drove expansively and nicked behind off Barker, who bowled his full stint straight off and was unlucky not to harvest better figures than 10-1-39-2.
Root and Gary Ballance added 64 in 14 overs before the latter lifted Grant Thornton to long-leg. Root, looking utterly assured, appeared set for his 11th List A century when he feathered an attempted cut at Clarke to the keeper.
That left Yorkshire 149 for 5 but Bresnan and Waite joined forces to exploit a short Hollies Stand-side boundary in a century stand. Considering the shortness of that boundary, for Patel (10-0-32-1) to deliver ten overs without conceding a four or six was a remarkable effort.
Still, Bresnan's ninth one-day half-century and Waite's first had given Warwickshire a stuff target.
Trott and Hain gave the Bears' reply an excellent base but after Trott sent up a skier off Waite, Rafiq struck three times in quick succession. He bowled Hain and Ambrose in the space of three balls and had Ateeq Javid caught at short fine-leg.
But Bell and Clarke halted the clatter and then gradually accelerated, Bell ending the group stage in fine form with scores of 93, 104 and 98.