Derbyshire 188 for 6 (Patel 67*) beat Leicestershire 184 for 6 (Cox 61*, Goldsworthy 48) by four wickets
Veteran allrounder Samit Patel tormented Leicestershire Foxes for the second time this Vitality Blast season as Derbyshire Falcons completed a double over their East Midlands neighbours in the North Group to lift their hopes of qualifying for the quarter-finals.
The 39-year-old Falcons skipper, whose 64 was the difference when the sides met at Edgbaston at the start of the campaign, hit nine fours and two sixes in an unbeaten 67 as Derbyshire chased down 185 to win by four wickets with four balls to spare.
Ben Cox hit four sixes in a 30-ball unbeaten 61 and Lewis Goldsworthy 48 from 41 as the Foxes finished strongly to post 184 for six. Former Leicestershire seamer Zak Chappell took three for 42 and Patel two for 27, with Pakistan left-arm quick Mohammad Amir wicketless on his Derbyshire debut.
Derbyshire had been well ahead of the required rate by posting 64 in their batting powerplay but had lost three of their key batters. Luis Reece edged behind off Mike, who then held a good low catch in the deep to remove the dangerous Aneurin Donald. Tom Scriven marked his return from a six-week injury absence by bowling David Lloyd, each of the trio falling to the eighth ball they faced.
Yet with fellow veteran Wayne Madsen (46) and Patel using their nous to find the gaps in the field, the Falcons were more than halfway to their target at 96 for three after 10.
They put on 80 in nine and a half overs before Madsen smacked Hull straight to New Zealand all-rounder Jimmy Neesham on the cover boundary. When Mike had Ross Whiteley leg before for a golden duck in the next over, the outcome looked less certain with 52 still needed off 33 balls.
Brooke Guest was caught off a top edge to give 19-year-old Sam Wood his first senior wicket but there was no pinning down Patel, who continued to find the rope as the last over arrived with the scores level, Chappell hitting the winning boundary.
Earlier, Patel had seen a quick reward for deciding to field first as the Foxes lost three wickets for 45 in the powerplay, with early indications that taking the pace off would be an effective tactic.
Chappell, hit for two fours and a six, responded by bowling Sol Budinger with a slower ball and held another one back a touch to similarly dismiss Rishi Patel, with Paul Stirling run out in between, his first innings for the Foxes ended by Madsen's direct hit from midwicket.
The home side slipped to 78 for five by the 11th over. Neesham's first innings as a Leicestershire player encompassed a stumping chance survived off Alex Thomson before he was bowled by Patel, with Louis Kimber following a big six over the leg side by hitting the left-arm spinner's next ball down straight to long off.
But Goldsworthy and Cox sensibly gave themselves time to get the measure of the pitch and their 48 off four and a half overs until the former was caught on the cover boundary created an opportunity for Cox to attack in the last four overs.
He had some luck on 10, his first attempt to clear the ropes dropped by Thomson, who lost the ball in the sun, but cashed in by hammering four sixes in the last four overs, scoring 44 of the 58 runs added.