Northants suffered disappointment at the hands of Durham as David Ripley's men were beaten by five runs in Sunday's Royal London One-Day Cup clash at the County Ground.
The Steelbacks had looked well set for victory when Alex Wakely (79) and Adam Rossington (66) were at the crease.
The pair produced a 129-run partnership to take Northants up to 167 for three before Rossington fell.
That sparked a real wobble in the Steelbacks reply as they were left 187 for seven after Durham's determined fightback.
The away side's chances of defending their 256 for seven, which came after they lost the toss, were increasing all the time.
Rory Kleinveldt did give Northants hope in typically powerful fashion as he lashed three fours and two sixes in his 41 from just 27 balls.
But when the South African all-rounder was bowled by Nathan Rimmington with four balls remaining, Northants still needed 10 runs.
And final-wicket pair Nathan Buck and Ben Sanderson were unable to find a way to the boundary as their team were just edged out.
Kleinveldt and Graeme White had the most joy with the ball for the Steelbacks, taking two for 50 and two for 46 respectively.
But Durham were able to defend their total to ensure Northants would taste a second defeat in four One-Day Cup matches this season.
Their next game is another 50-over battle as they take on Warwickshire in a televised clash on Wednesday (start time 2pm).