Northamptonshire 291 for 9 (Holden 68*, Duckett 53, Newton 50, Davis 4-55) lead Derbyshire 281 (Wilson 72, Buck 5-68) by 10 runs
A double career-best performance from Nathan Buck was the highlight of another hard fought day between Derbyshire and Northamptonshire in the Division Two match at Derby.
Buck followed figures of 5 for 68 with 43 out of a ninth wicket stand of 89 with Max Holden who made an unbeaten 68 as Northants recovered from 171 for 8 to reach 291 for 9 at the close in reply to Derbyshire's 281.
Will Davis with four wickets supported by sharp slip catching had put Derbyshire in charge before Buck and Holden kept their side in the game with a fighting partnership in the final session.
England batsman Ben Duckett and opening partner Rob Newton made half centuries to give Northants a solid platform but rash strokes transformed the contest after lunch.
Buck had taken two of the last four Derbyshire wickets in the morning as the home side added 62 runs with eighth-wicket pair Alex Hughes and Tom Milnes contributing 42 in 11 overs.
Northants had the best conditions to bat in and when Duckett and Newton were together in bright sunshine, it looked ominous for the home side until poor shot selection allowed Derbyshire a way back.
Duckett had reached 50 with successive fours off Sri Lankan legspinner Jeevan Mendis but he then aimed a big drive at Shiv Thakor and was well taken at second slip by Daryn Smit who did well to knock up an edge from Alex Wakely for Wayne Madsen to take a good reaction catch.
Madsen did even better with a one-handed grab to hold Newton's top-edged cut at Davis and when Northants lost four wickets in eight overs after tea, Derbyshire were poised to take a substantial first innings lead.
But Holden and Buck displayed the selectivity the recognised batsmen lacked to frustrate the home side for 20 overs with Buck straight-driving Mendis for six before he went back to the spinner and was lbw.
But that was not the end of Northants' resistance as Holden and Ben Sanderson gave their side a slender lead which had looked highly unlikely when Rory Kleinveldt was caught behind off Davis.
It all added up to a disappointing evening session for Derbyshire who also lost Thakor when he left the field with what appeared to be an ankle injury after he went over in his follow-through.