Durham beat Hampshire by six wickets at Chester-le-Street to overhaul their visitors at the top of Group B in the Yorkshire Bank 40 League.
Despite conceding 93 off the last 10 overs, Durham restricted the holders to 224-9 and lost acting captain Mark Stoneman in the first over of their reply.
A brief shower with the score on 55 for one in the 13th over reduced the target to 218 in 38 overs and, by the time Phil Mustard and Scott Borthwick had put on 164 for the second wicket, victory was a formality.
Mustard was dropped on 11 at slip by Sean Ervine off Pakistani left-arm paceman Sohail Tanvir and Borthwick survived a return chance to James Vince on 12.
Mustard went on to make 92 off 90 balls and Borthwick registered his maiden one-day fifty into 80 off 82 deliveries before holing out with 17 needed.
Borthwick hit sixes off both left-arm spinners, Danny Briggs and Liam Dawson, who had combined figures of 0-85 in 11 overs.
Tanvir took all four wickets to fall, producing excellent deliveries to clean bowl Stoneman and Ben Stokes. But only three were needed when he nipped one back off the pitch to breach Stokes' defence and Paul Collingwood saw Durham home with an unbeaten 32.
Hampshire were not helped by Dimitri Mascarenhas being unable to bowl following a back spasm, while Michael Carberry went for an X-ray after damaging a thumb.
For Durham, Chris Rushworth bowled with great control to take 5-42 after Hampshire were put in and the target looked like being much lower until Dawson thrashed 69 off 46 balls.