Having lost five of their first six matches and with the other rained off, things finally clicked for Northants as they powered to a crushing nine-wicket win over in-form Durham at Emirates Riverside.
The home side, who included England all-rounder Ben Stokes in their ranks, were restricted to 157 for five in their 20 overs, before Rossington hit 59 from 38 balls and Ricardo Vasconcelos a superb 78 not out from 57 balls to steer the Steelbacks home at 158 for one with 13 balls to spare.
It was a brilliant and very welcome batting performance, but Rossington chose to highlight the efforts of the spin bowlers, who between them snared five for 78 from 11 overs.
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Nabi claimed two for 24, White two for 31 and 19-year-old left-arm wrist spinner Heldreich one for 23, with his first senior wicket for the club seeing him bowl Ben Raine.
"It's nice to get that first win," said Rossington.
"We've been outplayed in a few games before this, but this was a real good performance from us all over the field.
"Freddie Heldreich was very good, and it's always lovely to see a lad take a wicket on his debut. He bowled brilliantly.
"Mohammad Nabi set the tone for us with the ball in the powerplay, and Freddie and Graeme White did a brilliant job for us.
"All three of them were fantastic."
It was also a timely return to form for the skipper.
Rossington had struggled for runs ahead of this game, scoring just 50 in five innings, but he more than doubled his tally here, with a highlight being when he took 14 runs off one Stokes over.
Vasconelos, promoted to open with Richard Levi being dropped, also showed what he is all about as he claimed a first T20 half century, and it was a very pleasing night.
"There's no doubt that we've struggled a little bit at the top of the order this year," admitted Rossington.
"But I think we had the best of the conditions, and once we got on top of them we were able to bat them out of the game."
Durham head coach James Franklin was disappointed with his team's performance, but praised the Steelbacks.
"We certainly weren't at the races," said the former New Zealand pace bowler.
"I actually thought we got a competitive total in the end after a slow start, but we got blown out of the water in the powerplay.
"Rossington played very well as did Vasconcelos, but it was very much a below-par performance from us from how we've been playing."
The Steelbacks remain bottom of the North Group, but at the halfway stage they do still have a chance of qualifying for the knockout stages, even if it is a slim one.
They are six points off fourth place and seven off second, and will be looking to build on the win over Durham when they host fifth-placed Lancashire Lightning at the County Ground on Friday night (start 6.30pm).