Con de Lange and James Middlebrook both took three wickets as Northants claimed their first FL t20 win at Glamorgan.
Middlebrook (3-16) and de Lange (3-15) restricted the home side to 110-9 from their 20 overs, with Stewart Walters (34no) top-scoring for the hosts.
Skipper Alex Wakely then hit 54 not out off 40 balls as the visitors reached their target from only 13.1 overs.
But the nine-wicket victory in Cardiff is not enough to lift Northants off the bottom of their group.
Glamorgan's chances of making the last eight are looking extremely remote after Saturday's defeat, a result that always looked likely once spin duo De Lange and Middlebrook had completed their devastating spells of bowling.
Middlebrook dismissed Mark Wallace and Chris Cooke with consecutive balls in the 12th over, before De Lange returned to trap James Harris lbw three deliveries later.
Opener David Willey got the Northants innings off to a flying start, hitting five boundaries in his 17-ball knock.
After Willey's departure, Wakely and Kyle Coetzer (28no) enjoyed an unbroken second-wicket stand of 77 to guide Northants to a comprehensive victory.
And Coetzer finished the match in style, smashing a huge six over mid-wicket off the bowling of left-arm spinner Dean Cosker.
Northants captain Alex Wakely told BBC Radio Northampton:
"I think (the win) has been coming for a long time. Things haven't gone our way this season.
"There's been a few 50-50 moments in this T20 season and things could have been different for us.
"I've got to take some of the blame as captain, but it's nice to get a win, because it was starting to get to me a little bit.
"Hopefully we can finish well and get people talking (positively) about T20 in Northampton again."
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