Nottinghamshire ended Group B leaders Surrey's unbeaten run in the Clydesdale Bank 40 with a five-wicket victory with all of 57 balls to spare.
With Harry Gurney taking 4-22 and Darren Pattinson 3-27, the Outlaws required just 124 for victory, which was never seriously in doubt after James Taylor - who made an unbeaten 41 off 57 balls - and Samit Patel had seized the initiative with a third-wicket stand of 57 in 14 overs.
Having elected to bat on the same pitch as the one that yielded over 900 runs for the loss of 12 wickets in the County Championship, Surrey slumped to 8-5 before recovering to make 123, their lowest total in one-day cricket for seven years.
The hosts lost Jason Roy to the third ball of the match, leg before to Patel, Steven Davies to the ninth, caught at first slip off Pattinson, and Gary Wilson to the 10th, caught behind.
With Zander de Bruyn falling to an excellent head-high catch at second slip by Adam Voges and Rory Burns toe-ending a drive off Pattinson to mid-on, the home side were in deep trouble.
But thanks to Matthew Spriegel, who countered with 39 off 76 balls, Surrey eventually found their feet.
Spriegel steered Harry Gurney down to the third-man boundary to ironic cheers, before clipping Pattinson through square leg for four.
But 10 overs later, Zafar Ansari lofted Jake Ball to Riki Wessels, who held on to a tumbling catch running back from mid-off to make it 46-6.
Spriegel was joined by Gareth Batty and together they added 43 in 11 overs. Batty despatched Patel to the rope at long-on and cover drove Steven Mullaney for four.
But Surrey were pegged back further when Gurney picked up three wickets in eight deliveries.
Batty, attempting to force the former Leicestershire man off the back foot, was caught behind for 24.
Spriegel, shaping to cut, had his off stump pushed back. Lewis edged behind and Michael Lumb drew a line under the Surrey innings when held on to a sharp chance at short fine leg off Ball.
In reply, Nottinghamshire lost Lumb to a run out, when Lewis pounced on Hales's defensive push to backward point off Spriegel.
Three overs later, Hales collected two successive fours off Stuart Meaker, only to depart a couple of balls later to a lofted catch at deep square leg.
Taylor cut a no-ball from Meaker for four before lifting the free hit back over the bowler's head. But shortly after despatching Batty to the rope at extra cover, Patel was caught at slip off Kartik.
With just 29 needed off 100 balls the writing was on the wall, notwithstanding the loss of Voges, who was caught behind looking to launch Kartik into the car park at the Railway End.
Having just been dropped at short mid-off, the gloss was taken off the Outlaws' victory when Wessels then fell to a leading edge off Batty.