Nathan Buck bagged five wickets for Northants, but they face an uphill task to rescue their Specsavers County Championship Division Two clash with Worcestershire at the County Ground.
The away side were dismissed for 434, giving them a first innings lead of 196.
Buck took five for 90, Ben Sanderson grabbed three for 74 and Rory Kleinveldt claimed two for 95.
But Daryl Mitchell’s 161 put Worcestershire in control and Northants were then left on 53 for two after the final 18 overs of day two.
Buck (6no) and Ben Duckett (25no) will be the men in the middle when the third day begins.
And when asked to reflect on his side’s bowling display, Buck said: “We bowled well in patches and produced periods of pressure but couldn’t contain as much as we’d liked and seemed to leak a few too many.
“The pitch didn’t do as much as yesterday and we didn’t put the ball in the good areas as consistently as we wanted to.”