Nili Latu scored with the final play of the game as Newcastle stole victory over Northampton at Franklin’s Gardens.
Newcastle laid siege to the Saints line as time ticked down and a quick tap-penalty led to Latu’s score.
The visitors led at half-time with tries from Sinoti Sinoti and Josh Matavesi, but with 10 minutes to play looked headed for defeat.
Saints went ahead through Dylan Hartley’s try after two first-half scores, but they failed to hang on.
It was a fifth-straight Premiership defeat for Jim Mallinder’s side as three returning England internationals failed to change their fortunes.
Yet for most of the second half, Saints looked to be moving towards a first Premiership win since September as Hartley burrowed over from close range to retake the lead.
The home side had struck first through Harry Mallinder’s smart first-half finish from 10 metres out and a surging maul that Toby Flood dragged down to concede a penalty try and a yellow card.
But Newcastle, far sharper than during the previous week’s defeat at home by Gloucester, scored through Sinoti and a first-phase move that ended in Matavesi’s try.
They were forced into long periods of defence to stay in the game but ultimately found a last-gasp try to halt their four-game losing streak in the Premiership.
Northampton director of rugby Jim Mallinder said:
“We dominated in the second half and we just couldn’t score. Then to concede in that final minute was really heartbreaking.
“We had a chance to win at Sale the week before, but we couldn’t score and lost the game. We’ve lost late on again today and it’s really hard to take.
“We’re not playing anywhere near as well as we have in the past and some of our basics are not right, but we’re also not getting the bounce of the ball and all that puts us in the position we are.”
Newcastle director of rugby Dean Richards said:
“Our defence was outstanding. Both sides made mistakes on the night but we found a way to win it.
“To still win in those circumstances was quite nice because we know there’s a lot more to come, and we put out a hell of a back line tonight.
“If we can get a little bit more out of that back division there’ll be some good results coming.”
Northampton: Mallinder; Estelles, Horne, Stephenson, Foden; Grayson, Reinach; Waller, Hartley (capt), Ford-Robinson, Paterson, Lawes, Wood, Gibson, Harrison.
Replacements: Haywood, Van Wyk, Hill, Ratuniyarawa, Eadie, Groom, Francis, Tuala.
Newcastle: Hammersley; Goneva, Harris, Matavesi, Sinoti; Flood, Takulua; Vickers, Cooper, Welsh, Green, Robinson, Welch (capt), Graham, M. Wilson.
Replacements: Lawson, Mavinga, S. Wilson, Witty, Latu, Stuart, Hodgson, Tait.
Yellow Card: Flood