Shiv Thakor and Andy Carter shared a whirlwind stand of 48 for the 10th wicket to give Derbyshire three batting points and a handy total of 324 on the second day at Northampton.
But afternoon rain prevented them making any progress with the ball as Northants made 66 for 0 in reply, trailing by 258.
Derbyshire resumed 275 for eight, hoping for their tail to survive long enough for Thakor to add to his overnight 60 not out.
But Luke Fletcher fell, bowled off stump by Muhammad Azharullah, to the fifth ball of the morning with just a single added to the score.
Any hopes Northants had of quickly ending the Derbyshire first innings were spoiled by Thakor and Carter who began a 37-ball partnership that added another 48 runs and handed the visitors a third batting point.
Thakor moved to 83 not out with five further boundaries, placing the ball cleverly with the field spread. Carter was far more recreational but slapped three boundaries in his 19-ball 17.
He eventually top-edged a hook to long leg, giving Azharullah a fourth wicket as the bowler finished with four for 95.
There was little to trouble Northants as they came out to reply before lunch.
A strong lbw shout against Jake Libby first ball of the innings went against Fletcher but there was no further danger as Libby and Ben Duckett settled well.
Duckett began to find his touch and wouldn’t have wanted to lunch break.
A wicked pull and cut came off Carter, followed by the stroke of the morning - a punched straight drive.
He struck seven fours in 36 not out.
Libby became more comfortable too on 28 not out before rain arrived eight balls after lunch.
It was largely drizzle but persistent and took out the afternoon.