Down clung on for a vital 1-09 to 0-10 victory over Donegal in the Allianz Football League Division 2 in Newry.
In an error-strewn display by both teams, Down led early on and were 1-06 to 0-05 ahead at the break thanks to Niall Madine's 13th-minute goal.
Down were denied a clear penalty in the eighth minute when Conor Laverty was dragged down by goalkeeper Paul Durcan.
Donegal hit 12 wides in a poor display but stay top of the table on scoring difference.
Both sides were guilty of poor distribution and spilling the ball when in possession but Down were a bit more clinical in front of the posts.
Madine got the only goal of the game after 13 minutes. Not for the first time, Down punched big holes through the middle of the Donegal defence and although Jerome Johnston's pass across the goal was missed by Donal O'Hare, Madine picked the ball up, turned and drilled it low through a crowded square and into the net.
Mark Poland was key to everything for Down and gave Leo McLoone a torrid time. Some of the Down players over-played the ball but Poland picked off two nice scores and hurt Donegal with his direct play.
Donegal were living off scraps and three of their scores came directly from Down mistakes.
Dermot Molloy got their first point in the 18th minute after Down defender Ryan Boyle had turned the ball over. He added a second point ten minutes later after Donal O'Hare made a similar blunder.
Michael Murphy showed a glimpse of his class with the best point of the opening half from near the sideline, around 50 metres out, as the 2012 All-Ireland champions stayed in touch despite hitting six first half wides.
Down opened up a five-point lead for the first time in the game through Madine's point in the last minute but a free from Colm McFadden deep into stoppage time reduced Donegal's deficit to four - 1-06 to 0-05 - at the interval.
Donegal came flying out of the blocks with two points in the opening two minutes of the second half from Martin McElhinney and McLoone.
Down responded through O'Hare (free) and Conor Garvey before Donegal talisman Murphy converted a '45' in the 44th minute to leave a goal between the sides.
The visitors then hit three terrible wides in quick succession, McFadden's free and David Walsh's effort being particularly poor.
The second period descended into mediocrity and neither side scored for a shocking 21 minutes.
Down only scored three points over the concluding 35 minutes yet still won the game, such was Donegal's profligacy.
Neil Gallagher was lucky to survive a sending-off for lashing out at Ryan Boyle, an episode which sparked a melee between the teams for a minute, while Laverty got a black card in stoppage time for hauling down Paddy McBrearty.
DOWN: B McVeigh; D McCartan, B McArdle, O Costello; R Boyle, A Carr, C Garvey (0-02); P Turley, K McKernan (0-01); C Laverty (0-01), M Poland (0-02), C Maginn; D O'Hare (0-02, 0-02f), N Madine (1-01), J Johnston.
Subs used: R Johnston for J Johnston (56 mins), B Coulter for Madine (68), P Fitzpatrick for Laverty (black card, 70).
DONEGAL: P Durcan; E McGee, N McGee, K Lacey; F McGlynn, L McLoone (0-01), A Thompson; R Kavanagh, M McElhinney (0-01); M McHugh, C Toye, O Mac Niallais; C McFadden (0-02, 0-02f), M Murphy (0-03, 0-01f, 0-01 '45'), D Molloy (0-02).
Subs used: N Gallagher (0-01) for Kavanagh, D Walsh for Mac Niallais, P McBrearty for Molloy (all 45 mins), D O'Connor for Toye (60).
Referee: Cathal O'Hagan (Tyrone)