The Steelbacks were unable to emulate their bowling brilliance against Birmingham Bears as they were beaten by Derbyshire Falcons on Friday night.
A week earlier, David Ripley's men had managed to defend a target of 133 from 16 overs, but there were no heroics in the field against the Falcons.
The away side eventually cruised to their victory target of 181 with 12 balls to spare as the Steelbacks struggled for wickets in the Vitality T20 Blast clash at the County Ground.
Captain Josh Cobb had earlier cracked a superb 84 from 50 balls, including seven sixes, as he passed 3,000 T20 runs.
Adam Rossington registered a half-century of his own but 180 for five wasn't to be enough as Derbyshire emerged from the powerplay unscathed.
And the Falcons eventually pushed on to secure their second victory in the North Group this season.
The Steelbacks went into the game with only that win against the Bears to their name and they got off to a sluggish start.
It was made worse by the fact Ben Curran again departed cheaply, being caught for three off the bowling of Ravi Rampaul.
It meant Cobb was tasked with helping opener Rossington to increase the early scoring rate, and he did just that, taking on Luis Reece during an expensive over.
It was to become a theme for the Falcons as the Steelbacks really started to accelerate.
Cobb reached his half-century from 34 balls as he continued to put the bowlers under pressure.
And Rossington joined his skipper in making it to 50 - from one delivery fewer - before Derbyshire eventually got the breakthrough.
Alex Hughes was the man with the wicket as he took a fine catch off his own bowling to get rid of Rossington.
The Steelbacks were still very well placed at 115 for two with seven overs to go, and they sent in Alex Wakely to provide support for big-hitting Cobb.
Cobb kept powering the ball over the boundary rope as the Falcons struggled to come up with any solutions.
But eventually Rampaul, who had bowled superbly in his opening spell, found a way to get rid of the rampant batsman, having him caught on the boundary by Leus du Plooy.
Rampaul had conceded just eight runs from three overs, taking two wickets in the process, as Northants made it to 152 for three with 18 Derbyshire deliveries remaining.
The Steelbacks were just slowing slightly and Dwaine Pretorius couldn't do anything about it as he was caught at deep square leg off Boyd Rankin.
But Wakely was playing extremely well, with some tidy shots finding the boundary and helping to elevate the run rate once more.
Rampaul again returned with a wicket though, with Wayne Madsen taking an impressive diving catch to dismiss Wakely for 27.
Matt Coles played a lovely shot to add four more to the tally as the Steelbacks finished on 180 for five.
But there were no early wickets for the hosts as the Falcons cruised to 52 without loss at the end of the powerplay.
The breakthrough eventually came when Cobb brought himself on to bowl, with the skipper dismissing the slow-scoring Billy Godleman for 14 from 20 balls.
Reece was doing most of the damage for Derbyshire, but Graeme White eventually got rid of him as Wakely took the catch just in from the boundary.
Reece had made 60 and Derbyshire were left on 98 for two with fewer little more than eight overs to go.
But Wayne Madsen soon steadied the ship as the Falcons took control of the chase, with the Steelbacks struggling in the field.
The hosts needed something special and Rossington provided it, flinging himself to his left to give Nathan Buck the wicket of du Plooy for 12.
With five overs to go, Derbyshire needed 41 from 30 deliveries and they had seven wickets in hand.
Ben Sanderson soon had Matt Critchley caught behind for five but Alex Hughes came in and notched a four then a six to get the chase back in his side's favour once again.
And Madsen continued to motor on, making a half-century as he took advantage of the Steelbacks' struggles with the ball.
Faheem Ashraf was forced to end his night five deliveries early after bowling one too many no balls, and the Falcons flew home.
Steelbacks: Curran, Rossington (wk), Cobb (c), Wakely, Pretorius, Coles, Keogh, Ashraf, White, Buck, Sanderson.
Derbyshire Falcons: Reece, Godleman (c), Madsen, du Plooy, Critchley, Hughes, Smit (wk), Hudson-Prentice, Watt, Rampaul, Rankin.