Leicestershire 178 for 6 (Eckersley 43) beat Durham 177 for 7 (Muchall 43, MacLeod 42) by four wickets
Leicestershire pulled off only their second NatWest T20 Blast success after Tom Wells hit Paul Collingwood for three sixes in the 19th over to set up a four-wicket victory at Chester-le-Street.
Collingwood had conceded only two runs off his previous over and removed Ned Eckersley for 43, but with 26 needed off two overs he began with a full toss which was driven over long on.
Wells pulled two more sixes over the short leg-side boundary and also hit a four courtesy of a misfield on his way to an unbeaten 31.With only two required off the final over, Ben Raine scored the winning runs against his native county as the Foxes got home with five balls to spare.
As well as the 19th, Durham also had a disastrous over in the 13th. Usman Arshad, previously impressive in this competition, bowled two waist-high no balls - one of which was hit for four - and had to be removed from the attack.
Scott Borthwick took over and after his first ball went for four byes Eckersley hit him for four and six and the over ended up costing 26.
After being put in on a glorious evening, Durham made their highest score in the competition this season of 177 for 7. Gordon Muchall led the way with 43 off 22 balls, while Callum MacLeod made 42 off 28 to take his aggregate in the competition to 250.
Despite making four more runs than they had previously managed this season, Durham never quite hit top gear on a run-laden pitch. They had 52 on the board after the six overs of Powerplay, but then Mark Stoneman fell lbw trying to reverse sweep Jigar Naik's first ball.
The offspinner also held a fierce return drive to remove Phil Mustard, just when the wicketkeeper had got going for the first time in this season's competition.
MacLeod again played well but got out attempting unnecessary improvisation when he stepped across to the off side and was bowled when trying to flip Charlie Shreck to fine leg.
A controversial incident in the 17th over could have been costly for Durham. In trying to catch Muchall at deep cover Rob Taylor appeared to knock the ball over the rope. He then knocked it back in again and in response to shouts from the crowd he raised his arms. Whether he was signalling six or merely shrugging was unclear.
There could be no proof of what had actually happened, so Durham had to settle for three runs and appeared to be unsettled by the confusion as Ben Stokes was run out for 20 off the next ball, then John Hastings drove a catch straight to extra cover.
Leicestershire skipper Josh Cobb said afterwards: "We've been playing good cricket without quite getting over the line, so it's great that Tom Wells got us there tonight."