Seamer Luke Evans tore into Gloucestershire's top order to set up a five-wicket victory for Northamptonshire in Monday's Second XI Trophy fixture at Dunstable.
Evans claimed the first three wickets to fall and finished with 4-22 from his eight-over stint as the visitors, in early trouble at 24-4 and 54-6, eventually limped to 157-8 in their 40 overs after winning the toss.
Usman Arif (2-33) also bowled effectively while Christian Davis amd Vicram Sohal picked up a wicket apiece.
Then it was the County's turn to struggle and they sumped to 24-3 in reply before Stephen Peters - continuing his comeback from a two-month injury lay-off - and Ricky Moore turned the innings around with a 90-run partnership.
Peters eventually departed for 50, but Moore (68no) and Zak Zhawaja finished the job at 158-5 with a couple of balls to spare.
The two sides begin a three-day Championship match at Campbell Park in Milton Keynes on Tuesday.