Durham were given a late scare before clinching a 39-run win over Lancashire in their Yorkshire Bank 40 match at Emirates Durham ICG.
The visitors were 162-8 in reply to 297-9 when Kabir Ali, making his Lancashire debut, went to the crease to join Jordan Clark.
They added 45 in four overs before Clark departed for a career-best 72, then Stephen Parry (10 not out) shared a last-wicket stand of 51 in six overs with Kabir.
The debutant thrashed five sixes, four of them off Chris Rushworth, in his 24-ball half-century before he was bowled for 59 by Ben Stokes with the total on 258.
Lancashire were all out with 3.5 overs left and last year's semi-finalists now have little chance of progressing after being outplayed by Durham for the second time in this season's competition.
Simon Katich invited Durham to bat in perfect conditions and acting captain Mark Stoneman (85) put on 126 in 14 overs for the first wicket with Phil Mustard (65).
The hosts never looked back, with Gordon Muchall following his 30-ball half-century against Derbyshire on Monday by making 48 off 33 balls, while Ben Stokes weighed in with 40 off 33 to set a competitive total.
In reply, Graham Onions proved a real handful for Lancashire, bowling straight through his eight overs to finish with 4-45 as the visitors fell short.