Inspired South Shields keep promotion hopes alive with stunning win on dramatic night at Mariners Park
The Mariners went in at half-time a goal down after an impressive first half performance by the Bucks, but responded instantly to turn the tie on its head.
Jon Shaw and Carl Finnigan netted within a minute of each other to put Shields in front, before defender Tom Dean was sent off for the visitors after two quickfire yellow cards.
Buxton did get back on level terms but Finnigan restored Shields' advantage and Josh Gillies made the game safe late on as the hosts marched on in front of a jubilant crowd.
They will host Warrington Town in the Evo-Stik Premier Division play-off final on Saturday, and the winners will progress to the super play-off final where they will battle for a promotion place.
Shields made two changes to the team which beat Gainsborough Trinity in the final league game of the season three days earlier, with Nathan Lowe and Finnigan introduced to the starting line-up in place of Phil Turnbull and Gavin Cogdon.
But they almost endured a nightmare start when a first minute corner by Buxton hit the head of Shaw before bouncing against the crossbar.
Buxton were one of the sides to avoid defeat against the Mariners in the league campaign, and they threatened again when Callum Chippendale flicked the ball onto Diego De Girolamo and he drilled an effort wide.
Shields had a number of half-chances but it was the visitors who struck first just before the half-hour mark.
Chippendale's shot from 20 yards was parried by Liam Connell and pounced on by De Girolamo as he smashed the ball home from close range.
The Mariners built up some momentum in the closing stages of the first half, but the closest they came was a sweet strike from distance by Craig Baxter which went wide.
Shields started the second half like a team possessed, and Buxton goalkeeper Theo Roberts was tested almost immediately by a 25 yard effort from Nathan Lowe.
From the resulting corner, the hosts pulled level as Gillies' cross was headed against the bar by Dillon Morse before Shaw forced home the rebound.
Less than a minute later, there was pandemonium at Mariners Park as Shields won the ball back and advanced down the left, with Blair Adams delivering an inch-perfect cross which Finnigan turned in from close range.
The Mariners continued to sense blood and almost scored again when Gillies played in Finnigan, who was denied by Roberts.
Buxton had a decent chance to equalise soon after, but Jude Oyibo could only head over after an impressive counter-attack.
Finnigan hit a further shot inches wide at the other end before Buxton were reduced to 10 men after two cynical fouls by Dean within a minute of each other each resulted in yellow cards.
Against the odds, the Bucks levelled things up in the 65th minute as a free-kick from a tight angle on the right of the box by substitute John Pritchard nestled in the net.
Their reprieve was short-lived, though, with Shields soon restoring their advantage when Lee Mason advanced down the right before sending in a dangerous low cross which Finnigan converted at the near post.
The Mariners effectively saw out the rest of the match, with Mason and Gillies going close before the game-clinching goal arrived a minute before the end.
Substitute Gavin Cogdon got in on the left of the box and although his effort was parried by Roberts, it fell to the feet of Gillies, who made no mistake in stroking the ball home from close range.
Shields must now win two further games at Mariners Park to clinch promotion.
Before that, they face Shildon in the Durham Challenge Cup final at the Stadium of Light on Friday.
SOUTH SHIELDS: Connell, Baxter, Adams (Lough 55), Shaw (c), Morse, Briggs, Daly, Lowe (Turnbull 66), Finnigan (Cogdon 79), Mason, Gillies. Subs not used: Mouanda, Foley.
Goals: Shaw (47), Finnigan (47, 71), Gillies (89).