Hampshire clinched an away Clydesdale Bank 40 semi-final when Somerset versus Surrey was declared a no-result shortly before their game with hosts Durham went the same way.
Both sides involved at Taunton could have pipped Hampshire to win Group B. However, their no-result left Hampshire level on points with Surrey but with one more win and Somerset a point further back. Hampshire's reward is a last-four date with Sussex.
When the Chester-le-Street match was called off with Hampshire 52-1 from six overs, it was confirmed that Saturday's Friends Life t20 winners had finished a point clear of last year's CB40 champions.
Rain prevented any play until 5pm, when it was announced that it would be 18-overs-a-side and Durham's acting captain, Mark Stoneman, put Hampshire in.
Ben Stokes opened up with a wicket-maiden, having Michael Carberry caught behind for a three-ball duck by Michael Richardson with regular wicketkeeper Phil Mustard patrolling the outfield.
Each of the next three overs, two of them bowled by Mitchell Claydon, cost 10 runs and then all-rounder Paul Coughlin conceded 15 in his one over of seam.
Durham handed CB40 debuts to Coughlin and off-spinner Ryan Pringle, both academy products from Sunderland.
The elegant driving of James Vince took him to 37 from 22 deliveries, while left-hander Jimmy Adams was unbeaten on 14.