Ian Harvey was the star for the Northants Steelbacks scoring 64 and then taking 3 wickets to help the Steelbacks beat the Glamorgan Dragons by 40 runs.
After winning the toss at Wantage Road, the hosts amassed 195-3 thanks to Harvey's 37-ball 64 and an unbeaten 55 from Riki Wessels.
The visitors reached 62-0 through Mark Cosgrove (40) and Jamie Dalrymple (24) before Nicky Boje removed Cosgrove.
Harvey (3-24) and Johannes van der Wath (3-23) then ran through the middle order to restrict the hosts to 155-9.
Northants' second win in as many games in this year's competition sees them leapfrog Glamorgan in the Midlands/Wales/West Division.