David Willey took his LV= County Championship wicket-tally to 15 in five innings with 4-71 on the opening day against Gloucestershire at Bristol.
Thanks largely to the left-arm seamer, the home side were restricted to 192 all out after winning the toss, 18-year-old wicketkeeper Cameron Herring top-scoring with 43 in his first championship innings.
Steven Crook, with 3-47, James Middlebrook - the beneficiary of two late wickets - and Trent Copeland, who conceded only 26 runs from 18 overs, provided able support for Willey, before the visitors replied with 107 for three.
The hosts delivered a tentative batting display and were nine for two in the seventh over when Willey followed up having Chris Dent taken in the slips by bowling Dan Housego.
Michael Klinger was caught behind playing forward to Crook for 23 and, with the ball moving in the air and off the seam, may have regretted his decision to bat.
Crook accounted for Alex Gidman, on 20, as he was caught at first slip by Andrew Hall and the score read 70 for five when Hamish Marshall was caught behind off Willey for eight in the final over before lunch.
Will Gidman offered a second catch to Sales to give the in-form Willey his fourth wicket.
Benny Howell looked in better form than most, but he had his stumps rearranged by Crook when pushing forward to make it 111 for seven.
Herring and Jack Taylor then put together an attractive stand of 48, which ended when off-spinner Middlebrook was introduced into the Northants attack.
The veteran accounted for Taylor, who skied to mid-off with 31 to his name, and David Payne was stumped by David Murphy off the medium-pace of Hall for a duck.
Herring, who had come in at 90 for six, was last man out, also stumped advancing to Middlebrook having hit eight fours in an 81-ball innings of immense promise.
The teenager's good day continued when he dived to catch Kyle Coetzer for 24 off Will Gidman to break a Northants opening stand of 41.
David Sales pulled a simple catch to midwicket off Liam Norwell and departed kicking himself for five.
Stephen Peters, on 34, repeated the shot against the same bowler and was brilliantly caught by Will Gidman at mid-on, but Northants could still be pleased with their day`s work.