Burnley overcame rough justice to snatch a precious point through Michael Keane’s last-gasp bullet header.
Moments earlier, with the Clarets pushing hard for a second equaliser, Keane was denied by a farcical refereeing decision after his header had clearly crossed the line.
But Sean Dyche’s never-say-die side shrugged off the frustration and righted the wrong in sensational fashion to extend their unbeaten run to 16 games.
Earlier, Andre Gray’s 23rd goal of the season cancelled out Dale Stephens’ opener, before Anthony Knockaert restored the hosts’ lead with a deflected 45th minute strike.
And the stunning events at the Amex duly kept Albion at arms’ length as the season draws to breathtaking climax.
Ashley Barnes returned to the squad for the first time since May in the only change to the 18 that drew with Wolves last time out.
Barnes replaced Rouwen Hennings on the bench in front of Albion’s biggest home crowd of the season.
And Burnley wasted no time setting about their toughest test of the season, as Gray tested David Stockdale with a drive from distance in the first minute.
Joey Barton failed to connect cleanly David Jones’ second corner in a matter of minutes as the Clarets’ composed start continued.
Liam Rosenior blazed over from Albion’s first foray forward, as the hosts looked to counter quickly at every opportunity.
But the visitors continued to probe and from a long ball forward midway through the half, in-form Sam Vokes chested down and volleyed tamely wide.
However, on the half hour, Albion opened the scoring. A corner flicked off Matt Lowton’s head to the far post where Stephens somehow bundled the ball home from the tightest of angles.
It needed a response – and it got one within three minutes as Burnley equalised.
David Jones’ corner was flicked on by Michael Keane and when Stephen Ward kept the ball alive at the far post, Gray pounced to rifle home the loose ball from inside the six-yard box.
Suddenly, the game sprung to life and Tom Heaton had to be alert for the first time to claw away Sam Baldock’s rising effort.
And on the stroke of half time, the hosts restored their lead on another counter.
Knockaert received the ball in the right channel and turned and twisted before finding the net via a deflection off the unfortunate Keane.
Suddenly Burnley were on the back foot and after Tomer Hemed headed a deep cross flush off the face of the post, Heaton did well to turn away Knockaert’s fierce follow-up in the last action of the half.
There was a more sedate start to the second half, with the Clarets again probing in search of the second equaliser.
And as the hour mark passed, Matty Taylor was introduced for Arfield, who had passed a late fitness test on the back injury he sustained making his international debut for Canada.
But it was Brighton who looked to extend their lead following another of their trademark counter attacks.
This time, substitute James Wilson crossed low for Knockaert, who forced a fine save from Heaton with a first time effort.
Dean Marney replaced Jones with 18 minutes remaining, moments before Vokes headed just wide from a cross from Ward.
And with 10 minutes remaining, Barnes returned to the starting line-up against his former club in the hope of providing a fairytale finish.
Instead, there was a nightmare scenario for the officials, who missed the fact that Keane’s powerful 88th minute header from Taylor’s corner had crossed the line.
The instant reaction from Burnley’s players told everyone inside the Amex they felt they had been robbed of a point.
But that was salvaged moments later to spark sensational scenes, with the players celebrating with the Burnley fans massed behind the goal in what could prove a pivotal day.
BURNLEY: Heaton, Ward, Mee, Keane, Lowton, Arfield (Taylor 66), Barton, Jones (Marney 72), Boyd, Vokes, Gray (Barnes 81).
Subs: Robinson, Kightly, Tarkowski, Darikwa
BRIGHTON: Stockdale; Bruno (Bong 81)), Goldson, Dunk, Rosenior; Knockaert, Stephens, Kayal, Murphy; Hemed (Sidwell 85), Baldock (Wilson 43).
Subs: Maenpaa, Greer, LuaLua, Skalak.
Ref: C Pawson
Att: 29,683 (1,633)