Brighton secured an FA Cup semi-final clash against Manchester City as the Seagulls beat Millwall in a penalty shoot-out to complete a remarkable comeback.
Millwall appeared on course for what would have been a routine and well-deserved victory as Alex Pearce's 70th-minute header and an Aiden O'Brien goal had them two goals ahead with two minutes left on the clock.
But Brighton's substitutes got them out of trouble, Jurgen Locadia halving the deficit with a fine strike before David Martin flapped badly at a last-gasp Solly March free-kick to draw the visitors level at 2-2 and send the tie into extra-time.
Shane Ferguson was sent off at the death for kicking out at Lewis Dunk - before Lions defender Jake Cooper missed the decisive penalty, firing high over the crossbar as Brighton won 5-4 on penalties.
The result means Brighton have reached the FA Cup semi-finals for only the second time in their history, with City now standing in their way of reaching the final for the first time since 1983.
The hosts started on the front foot, Jed Wallace steering a shot wide before striker Lee Gregory, passed fit to play after suffering a calf injury in midweek, fired over.
A scrappy first 25 minutes saw both sides tussling for possession with neither able to take control of the tie, Beram Kayal slipping as he struck Brighton's first shot on goal and allowing Martin to make a routine stop.
Kayal missed the best chance of the half as he could only head tamely at Martin after getting onto the end of Anthony Knockaert's cross.
Millwall almost benefited from a defensive mix-up early in the second-half, Ryan hitting his clearance onto Duffy from point-blank range before recovering in time to prevent Gregory taking advantage.
With the wind and rain intensifying, the chance of more errors was heightened - but Martin did well to get down low and pad away a Kayal shot from outside the box.
Ryan was also called into action, narrowing down the angle before saving Wallace's strike as the game started to open up - with Millwall skipper Shaun Williams drawing another stop from the Brighton goalkeeper soon after.
The hosts were again asserting superiority and Ryan prevented Gregory from opening the scoring before Cooper headed the resulting corner wide at the back-post.
They would not be kept out at the next time of asking, however, as Pearce arrived unmarked to bullet a header past Ryan and give Millwall the lead with 20 minutes remaining.
Everything seemed to be set for Millwall to reach Wembley with a memorable win as O'Brien turned in Wallace's low cross - only for Brighton to finally respond.
Locadia's crisp turn and finish two minutes from time set the scene after he had been brought on to replace the ineffectual Knockaert.
Brighton secured a reprieve their performance barely merited as March sent a stoppage-time free-kick into the box with Martin - strong in the Millwall goal for much of the game - allowing the ball to float in over his head.
Millwall did not let their heads drop and started extra-time well, James Meredith's low shot palmed away by Ryan as Mahlon Romeo blazed the rebound over.
Martin was equal to March's next effort and the Millwall defence coped well in the closing stages of extra-time as Brighton camped out on the edge of their penalty area.
Ferguson was given his marching orders in the final minute of extra-time after kicking out at a prone Dunk, Locadia seeing a goal then ruled out for offside as the game went to penalties.
Glenn Murray smashed the crossbar with the first spot-kick to give an early advantage to Millwall, who converted their first three efforts only to see Ryan keep out Romeo's effort with his foot.
Stephens and Steve Morison then scored for their respective sides to take the shoot-out into sudden death, where Cooper blazed over the sixth penalty to send Brighton to Wembley.
Reaction
Brighton captain Dunk told BBC One: "It was crazy. We did it the hard way. We knew it was going to be hard coming here and we made it even tougher for ourselves at 2-0 down and fighting back. An amazing day.
"It shows what great character we've got. We've done it for four or five years now, since the gaffer's been here. We never give up and we always fight. Massive credit to all the boys who dug in."
Seagulls boss Chris Hughton said: "I think that is what you call a proper cup tie. I didn't think we did well enough in the early part of the game. It's a very difficult place - they have a history in this cup competition.
"But it's about character. I think at 2-0 down with the thought of going out of the competition, we had a group of players that decided they desperately wanted to stay in the cup.
"At 2-0 down you have to go for it and you look for the moments and of course we managed to get them."
On the dramatic equaliser, Hughton added: "As soon as Solly put the ball in our initial reaction was one of disappointment cos he's overhit the ball.
"But sometimes you need those moments and we probably didn't craft out enough to turn the tie, but a little bit of fortune (went) our way. But you have to give our lads credit."
Opta facts
- Brighton have qualified for the FA Cup semi-final for just the second time in their history - previously doing so in 1983 when they finished as runners-up.
- Brighton are just the third side to reach the FA Cup semi-final stage after winning on penalties after Sheffield United (1993 and 1998) and Arsenal (1998).
- Brighton have won eight of their last nine penalty shootouts in all competitions, winning each of the last three in the FA Cup.
- Millwall have lost seven of their last eight penalty shootouts, losing their last two in the FA Cup.
- Millwall are unbeaten in their last six home FA Cup matches against Premier League opponents (W5 D1), last losing in February 2012 against Bolton Wanderers.
- Millwall are winless in their last five home games in all competitions (D3 L2), their longest run without a win at the Den in a single season since March 2015 (13 games).
- Millwall's first seven goals in the FA Cup this season came from set-pieces (free-kick x4, corner x3), with Aidan O’Brien’s goal the first from open play.
- Jed Wallace has either scored or assisted in each of his four FA Cup games for Millwall at the Den (one goal, three assists).
- Jürgen Locadia’s goal was his first in 19 away games in all competitions for Brighton, with his other five coming at home at the Amex Stadium.