Northants 338 (Holden 124, Cobb 96, Rossington 65, Coughlin 5-49) and 44 for 1 require a further 161 runs to beat Durham 166 and 376 (Steel 128, Collingwood 54, Azharullah 5-72)
Skipper Alex Wakely led the way with 83 as Northamptonshire defied the elements and sealed a dramatic two-wicket win with one ball left in the Specsavers County Championship match at Chester-le-Street.
With the floodlights on for the last ten overs and steady rain falling in the final ten minutes, the visitors finished the task of scoring 100 in 17 overs by scampering a bye to the wicketkeeper.
Needing 161 with nine wickets standing, no play was possible until 3.05 and tea was taken after 35 minutes when 56 had been added in nine overs. That meant a further 105 were required from 33 overs, but only one over was bowled after the break before the rain returned.
The 5pm resumption favoured the NatWest T20 Blast holders against Durham's inexperienced attack, who were bravely led by Paul Coughlin, who finished with match figures of 10 for 133.
Rob Newton cut and pulled Gavin Main for two fours in the second over of the final chase to reach 50 but then miscued Coughlin to deep mid-on to end a stand of 123.
Wakeley, who had begun the day on 18 and raced to a 58-ball half-century before the break, continued to score at the required rate and had the target down to 47 when he was narrowly run out attempting a second run to deep point.
Rob Keogh skied a return catch to Coughlin and Rory Kleinveldt holed out at long-off. But Barry McCarthy was denied a second wicket when, with 26 needed off four, Josh Cobb was dropped at long-on by Michael Richardson.
The last ball of the over soared over the same fielder for six and Cobb, the match-winner against Durham in last year's T20 final, had all but finished the job when he was caught at third man in the final over.
Wakely said: "We tried our best to lose it at the end, but we had the upper hand from the first day and it's a good feeling to come away with a win we really needed.
"The weather threatened to deny us, but we were always holding on to a hope that there would be an opening and we felt 20 overs at the end was all we needed."
With his side even further adrift than at the start of the season, Durham coach Jon Lewis said: "We were well aware of the size of the points deduction, so that's not an excuse. The loss of personnel is a bigger factor. We are a bit light on battle-hardened campaigners and need to work on maintaining standards over four days."