Donal O'Hare kicked a magical nine points tally to lead Down to their first NFL win of the season.
The Mourne men saw off Mayo by 0-13 to 0-11 at Pairc Esler to give themselves a fighting chance of avoiding relegation.
O'Hare converted there frees to help the home side come from behind to lead 0-6 to 0-4 at the break, after Jason Doherty and Michael Conroy had edged last year's beaten All-Ireland finalists in front.
Down needed a superb save from Brendan McVeigh to deny Barry Moran as Mayo took control in the second half, but the westerners were never able to get their noses in front.
They did go level when goalkeeper Kenneth O'Malley converted a '45 five minutes from the end, but two late scores from O'Hare sealed the points for James McCartan's side.