Alan Richardson took three wickets as Worcestershire just about managed to stay in contention against Northamptonshire on the first day of their LV= County Championship match at Wantage Road.
After being put in to bat, Worcestershire were bowled out for just 196 with Moeen Ali's 79 the only innings of note as Andrew Hall and Trent Copeland took 3-45 and 3-51 respectively.
The in-form Richardson then claimed 3-43 to revive the visitors' hopes as Division Two leaders Northamptonshire closed a frenetic day's action on 100 for four.
Australia international Copeland, playing in his last match before returning home, wasted little time in trapping Worcestershire captain Daryl Mitchell lbw for one.
Fellow opener Matt Pardoe plundered 22 before he left a Steven Crook delivery that clattered into the top of off stump.
Thilan Samaraweera then came to the crease, although he was to only make 16 prior to seeing his middle stump uprooted by a Hall delivery that nipped back through the gate.
Worcestershire finished the morning session on 100 for three, only for Hall to bowl Alexei Kervezee for 19 in the second over after lunch.
Aneesh Kapil made it to four before he was superbly run-out by Crook's direct hit from cover after Moeen attempted to run a quick single off David Willey in the following over.
Moeen went on to complete his half-century off 99 balls, but wickets continued to tumble at the end other end as Michael Johnson was bowled by Hall.
Gareth Andrew was the next to perish, pinned lbw by Crook, and Jack Shantry edged Copeland to third slip.
Moeen’s resistance was broken when he flicked Willey's bouncer to Northants wicketkeeper David Murphy, with Copeland ending Worcestershire's innings when Chris Russell chipped to Willey at mid-off.
However, Northants lost Matthew Spriegel and Kyle Coetzer in the first over of their reply, taken by Moeen and Mitchell at first and second slip respectively off Richardson.
Northants captain Alex Wakely made a bright 31 before mistakenly leaving an Andrew delivery and having his off stump taken out.
David Sales, having made a season-high score of 40, was then trapped lbw by Richardson with the last ball of the day, with Rob Keogh set to resume tomorrow on 26.