A last-minute goal by Cedric Main gave Darlington a deserved victory and earned a place in the next round of the FA Trophy following a much-improved second half.
Buxton had the better of the first 45 minutes at Blackwell Meadows, and a repeat of their 2-0 victory in August over Quakers looked on the cards.
Ethan Fitzhugh and Josh Popoola scored when the teams met three months ago, and both had chances early in this meeting.
Fitzhugh saw a low shot saved easily by Peter Jameson, and Josh Popoola headed over after meeting Jack Stobbs’ right-wing cross.
Buxton kept possession for lengthy spells but failed to seriously trouble Jameson, while Quakers’ Jack Maskell missed a simple chance just before half-time.
Presented with what should have been a tap-in after good work by Main to send over a cross from the right, Maskell somehow missed the target from close-range.
The 20-year-old striker was withdrawn just before the hour mark when Quakers boss Steve Watson made a double change, sending on Caden Kelly and Matty Cornish, and thereafter Darlington took off the shackles and the game swung entirely in their favour.
They created numerous chances with Buxton goalkeeper True Grant, on loan from Manchester City, called into action several times.
Cornish caught the eye in his most effective showing since last season; he whipped a side-footed effort wide from the edge of the box, and then played in Cameron Salkeld, but his low shot was parried by Grant.
Grant tipped wide when on-loan Kelly cracked a low shot seemingly headed for the bottom corner of the net, and the attacks kept coming with defender Toby Lees next to have a go, trying an audacious chip from 20 yards, easily gathered by the goalkeeper.
With no extra-time to be played, penalties were looming. But Darlington had other ideas.
Will Hatfield made a penetrating run into Buxton territory, dribbling with the ball from halfway into the opposition half, before giving the ball to Main, and the striker shrugged off a defender before hammering home from 14 yards to clinch victory.
Referee: Mark Bell
Attendance: 995
Darlington (4-3-3): Jameson; Griffiths, Lees, Barrow, Rivers; Flint, Hatfield, Alshabeeb (Kelly 59); Salkeld, Main, Maskell (Cornish 59). Subs not used: Hedley, Platt, Rudd
Buxton (3-4-3): Grant; Delap (Williams 27), Mann, Burton; Stobbs, Kirby, Coleman, Popoola; Fitzhugh (Trueman 70), De Girolamo (Tomlinson 64), Elliott. Subs not used: Leigh, Rose
