Cameron White's destructive half-century saw Northamptonshire into the Friends Life t20 finals day for only the second time as they beat Durham by 36 runs at Wantage Road.
A strong showing with the bat proved decisive as the hosts, led by former Australia international White, who thrashed 58 from 32 deliveries, produced a polished performance.
Ben Stokes gave Durham brief hope although his unbeaten 51 off just 29 balls came too little, too late.
Having won the toss and electing to have bat first, the Steelbacks made steady progress in the initial stages.
David Willey, promoted to open, joined Kyle Coetzer and the pair made efficient use of the six-over powerplay which ended at 40 without loss.
It was not spectacular, a decent spell from Graham Onions saw to that, but enough impetus was created for the required acceleration.
That came primarily from Willey who flailed his way to a 34-ball 46 before an intended sweep saw him bowled by Gareth Breese.
Coetzer fell shortly after the hundred mark was reached when a smart piece of work from Phil Mustard caught him short of his ground and that set the stage for White.
The Australian duly obliged with a trio of sixes in one Breese over - the 16th - which advanced the score from a potentially average level to one with much more substance.
White motored to his 50 from only 27 balls and with Alex Wakely (20 from 14 balls) lending good support, 79 runs came from the last six overs as the hosts posted a challenging 183 for four.
The reply didn’t start too promisingly as both Mustard and Mark Stoneman struggled to get going, and it was no surprise when the latter lost his middle stump to Steven Crook.
Already behind the rate, the visitors just could not find the boundary with any regularity, and at the halfway point a further 131 runs were needed.
The longer Stokes stayed on the sidelines the less chance Durham had, and his arrival in the 12th over when Mustard departed for 46 offered a flicker of hope.
While the promising, big-hitting all-rounder landed a handful of meaty blows in a rapid half-century, it was to no avail as they fell comfortably short on 147 for six.
NATWEST is to become the new sponsor of English Twenty20 cricket in a four-year deal starting next summer.
The England and Wales Cricket Board has signed a “ground-breaking“ contract, agreeing NatWest not only as the new backer for domestic Twenty20 - currently sponsored by Friends Provident - but all short-format matches in this country, including internationals.
That will cover England’s eight Twenty20 fixtures against Sri Lanka, India, New Zealand, Australia, Pakistan, the West Indies and South Africa in the contract period.
NatWest, whose backing of home one-day internationals concludes this year, will also become the lead sponsor of the national Twenty20 club competition and title sponsor of the women’s Twenty20.
ECB chief executive David Collier said: “NatWest has been a wonderful and loyal supporter of cricket over the past three decades.
“ECB is delighted that this long-standing partnership will continue.”