Derry 0-12 Down 0-11
Derry survived a superb second-half comeback by 14-man Down as Eoin Bradley tapped over an injury-time free to snatch a precious 0-12 to 0-11 Ulster SFC victory at Celtic Park.
The home side took their foot off the gas when they led by 0-10 to 0-06 after 41 minutes after Down sweeper Conall McGovern had picked up a straight red card at the start of the second half.
Down played their best football when reduced to 14 men, with Conor Laverty pulling the strings and Mark Poland picking up a number of fouls which Paul Devlin converted.
Derry failed to score for 21 minutes as Down reeled off four points in a row to draw level, but Bradley's last-gasp free secured a first win in Ulster for Derry since 2011.
After a quiet opening, Fergal Doherty and Mark Lynch came to the fore and combined to steer Derry into a 0-08 to 0-05 half-time lead.
The sides were level twice in the opening nine minutes, Eoin Bradley and Kevin McKernan both scoring and starring for their respective sides.
Bradley scored three points in the first 14 minutes, two from frees, and won a lot of possession in the Derry full-forward line.
Enda Lynn also scored from play after patient build-up play as Derry opened up a 0-04 to 0-02 lead after 19 minutes.
Derry's excellent full-back line bottled up the Down forwards, who were guilty of rushing their shots. Poor shot selection contributed to five wides in the opening half, midfielder Peter Fitzpatrick hitting one terrible wide from close range after being teed up by Conor Laverty.
At the other end, Mark Lynch also had a bad start, with three wides, before he converted his first free in the 24th minute. The score lifted him and he hit three subsequent points from play before the break.
Paul Devlin nailed two first-half frees for Down and Kevin McKernan was the key performer, collecting a pass from Conor Maginn who split the posts after 32 minutes to leave the visitors trailing by 0-06 to 0-05.
The Oak Leaf county were more clinical with their chances, waiting to get the right man on the end of a lot of their shots.
After a subdued start, Fergal Doherty caught two kickouts in the closing moments to inspire Derry, and on both occasions, Mark Lynch got on the end of the move to score a valuable brace.
The first came after the ball was recycled back to him 40 metres out and he hit a majestic point from near the sideline just before the whistle blew to put Derry three points up for the first time in the game.
Things got even better for Derry on the restart when Conall McGovern received a straight red card for an apparent strike on Enda Lynn after the throw-in.
McGovern had been deployed as Down's sweeper and after his departure they went man-to-man.
Initially, Derry profited with the extra man as a Lynch free and a superb point from Bradley, who shrugged off two defenders to score with his trusty left foot, put the home side 0-10 to 0-06 up after 41 minutes.
However, from nowhere, 14-man Down suddenly wrestled the initiative away from Derry and reeled off four points in a row in an eight-minute spell to draw level.
Paul Devlin converted three frees before Conor Laverty, who had fisted the opening point of the second half, scored a screamer from the wing to tie the scores after 56 minutes.
Laverty pulled the strings and orchestrated for Down but they were left to regret seven second-half wides in a dramatic finish.
Derry sub Caolan O'Boyle ended a 21-minute scoring drought with a fisted point after good work by Eoin Bradley and Kevin Johnston to put a nervous home team back in front with nine minutes remaining.
Paul Devlin hit his sixth free of the afternoon to bring Down level again after 67 minutes and the game was in the melting pot at 0-11 apiece.
Derry worked one last move, with Eoin Bradley releasing Kevin Johnston close to goal. He was dragged down by Darren O'Hagan, who picked up a black card, and Bradley tapped over a close-range free as Derry stumbled over the line and into an Ulster semi-final against Armagh or Donegal.
Scorers for Derry: M Lynch 0-05 (2f), E Bradley 0-05 (3f), E Lynn 0-01, C O'Boyle 0-01 to
Scorers for Down: P Devlin 0-06 (6f), C Laverty, K McKernan 0-02 each, D O'Hare 0-01 (f)
DERRY: T Mallon; O Duffy, B Rogers, D McBride; K Johnston, C McKaigue, C McFaul; N Holly, F Doherty; SL McGoldrick, M Lynch (0-5, 2f), E Lynn (0-1); B Heron, E Bradley (0-5, 3f), D Heavron
Subs: C O'Boyle (0-1) for Heron (53), T O'Brien for Lynn (63)
DOWN: S Kane; D O'Hagan, L Howard, R Boyle; D Turley, B McArdle, C McGovern; P Fitzpatrick, C Mooney; P Devlin (0-6, 6f), C Maginn, K McKernan (0-2); M Poland, C Laverty (0-2), D O'Hare (0-1, f)
Subs: P Downey for Maginn (48), J Johnston for Fitzpatrick (60), A McConville for Mooney (66), N Madine for Devlin (69), D O'Hanlon for O'Hagan (BC, 70)
REFEREE: Eddie Kinsella (Laois)