Seamer Sam Sweeney snapped up three wickets in the final session following an up-and-down batting display by Northamptonshire in their Second XI Championship match agaimst Surrey at Campbell Park.
Sweeney's triple strike reduced the visitors from 35-0 to 39-3 in reply to the County's 289 all out - but Surrey progressed to 83-3 at the close, trailing by 206.
Northamptonshire made an excellent start after winning the toss with Cumberland's Josh Tolley (67) and former Surrey left-hander Tom Lancefield (74) sharing an opening stand of 153 in 40 overs.
But the County collapsed in spectacular fashion to 170-6 - losing six wickets for 17 in half-a-dozen overs - before useful lower-order runs from Luke Blackaby (41), Lee Daggett (28) and Sweeney (29) ensured a decent final total.
Northants will be looking to break through again when play resumes in Milton Keynes on Wednesday morning.