An impressive partnership between Cameron White and captain Alex Wakely helped Northants Steelbacks end Glamorgan's 100% record in the Friends Life t20 with a dramatic seven-wicket win that halved the Welsh County's lead in the Midlands, Wales & West Group.
Glamorgan posted 153 for seven as veteran Murray Goodwin top-scored with 47 off 31 balls, Mohammad Azhar Ullah taking personal-best Twenty20 figures of 4-14.
The Steelbacks then reached their target off the final delivery of the match thanks to White hammering a 52-ball 68 and Wakely an unbeaten 52 from 39 deliveries.
After Northants chose to field, Glamorgan captain Jim Allenby fell on 36 when launching Azhar high into the air, the catch taken by wicketkeeper David Murphy.
The hosts continued to hit back as Chris Cooke struck Matthew Spriegel to Lee Daggett at deep midwicket before Murphy stumped Mark Wallace for 19 off the same bowler.
Ben Wright was then bowled for 15 by James Middlebrook and Graham Wagg knocked the bails off with his bat to gift Azhar his second wicket.
The Pakistani seamer claimed two more victims in the final over as he was hammered by Nathan McCullum to David Willey at deep point before Goodwin sliced to Murphy.
Northants lost Kyle Coetzer in the second over; he hit Allenby to Alex Jones at deep square-leg as the hosts fell behind the run-rate early on.
South Africa international Richard Levi departed on 24 when Dean Cosker's delivery spun into his off stump before Wakely was dropped on 13 by Goodwin at backward point off the same bowler.
White went past 50 off 43 balls by blasting a six down the ground off Michael Hogan as Northants tried to claw their way back into contention in the last four overs.
Wakely completed his half-century off just 35 deliveries and, after White was run out by Nick James at backward point, Steven Crook's four off Hogan sealed the win.