Match ends, Lincoln City 3, Brighton and Hove Albion 1.
Lincoln City reached the last 16 of the FA Cup for the first time in 115 years with a superb victory over Championship leaders Brighton at Sincil Bank.
Brighton went in front through Richie Towell but the National League leaders mounted a superb second-half recovery.
Alan Power's penalty began the fightback before Fikayo Tomori put the ball past his own goalkeeper.
Theo Robinson, who scored twice at Ipswich in the third round, added the third on the break.
The result sees Brighton eliminated from the FA Cup by non-league opposition for the first time since 1998, when they lost to Hereford United.
- BBC One is showing two live FA Cup ties on Sunday. Millwall host Watford at 12:00 GMT, followed at 16:00 GMT by holders Manchester United against Wigan.
Lincoln show battling qualities
Brighton made nine changes for this match but they nevertheless began well with Glenn Murray bringing a good save from Paul Farman with a header and Solly March rattling the crossbar from long range before they opened the scoring.
A long ball forward was knocked on by Murray into the path of Towell, who flicked a cool first-time finish beyond the advancing goalkeeper.
Danny Cowley's hosts were some way short of the hugely impressive performances they put in against Ipswich in the last round - first in drawing at Portman Road and then winning the replay - but always looked dangerous going forward, with burly striker Matt Rhead a constant threat.
But it was Rhead's strike partner Robinson who was instrumental in the Imps pulling level, grappling with Murray as they competed for a free-kick and rightly being awarded a spot-kick, from which Power made no mistake.
The hosts went in front when Nathan Arnold - who scored a last-minute winner against Ipswich - sent over a cross from the right that on-loan Chelsea defender Tomori contrived to steer into his own net.
And the result was put beyond doubt five minutes from full-time when Robinson fired home a clinical finish after a quick break to register his fifth goal in this season's competition.
'An unbelievable story'
Lincoln's achievement in beating a team 72 places above them in the football pyramid puts them into the last 16 of the competition for the fourth time, after previously achieving the feat in 1887, 1890 and most recently in 1902.
The last time they reached what was termed as the "fifth round" was actually 1887, before changes to the format resulted in the last-16 stage being categorised as an earlier round.
While FA Cup scholars argue over whether Lincoln are now on their best FA Cup run in 115 years or 130, their players will concern themselves only with who now awaits them in the next round.
"I'm speechless at the minute," Lincoln striker Arnold told BBC Radio 5 live. "It was a magnificent effort in the second half and our run continues."
Robinson, meanwhile, said the result "shows our attitude - we keep pushing to the end and it pays off".
"We all know what we have to do and we all want to achieve something great," he added.
Five live summariser Chris Waddle said: "Brighton deserved the lead in the first but after that second-half performance, Lincoln thoroughly deserve the result.
"They've had an unbelievable story and they look like they are ready to give anyone a game in the competition."
Former Everton winger Kevin Kilbane told Final Score: "Lincoln deserve a great draw now, a Chelsea, an Arsenal or a Manchester United. Hopefully they'll get it. And if they could take them to Sincil Bank that would be even better."
'Beyond my wildest dreams' - manager quotes
Lincoln manager Danny Cowley, speaking to BBC Sport: "You always go into games thinking you have a chance. The boys were organised and motivated.
"I'm surprised. It's not often football surprises me, but today...
"I was really pleased that we were able to stay in the game. Half-time gave us a chance to regroup. We were brave all afternoon - we wanted to press high and be committed to our style and what we believe in.
"I can't believe the scenes and the emotion and the support. It's beyond all of my wildest dreams."
Brighton boss Chris Hughton: "It was certainly not a result I would have seen coming at half-time
"We were in decent control at half-time but what you can't afford is to give them a leg-up, and when you concede three goals as poorly as we have, that makes it difficult to win any game.
"If I look at the goals we conceded, they are all errors."
On his decision to make nine changes to his team, he said: "I would do it again."
- 2WoodBooked at 41mins
- 8PowerBooked at 35minsSubstituted forMcCombeat 90+8'minutes
- 9RheadSubstituted forLongat 88'minutes
- 31RobinsonSubstituted forMuldoonat 87'minutes
- 1MäenpääSubstituted forAnkergrenat 56'minutes
- 27TomoriBooked at 37mins
- 21NorwoodBooked at 90mins
- 8SkalakSubstituted forMurphyat 68'minutes
- 29TowellBooked at 24minsSubstituted forHemedat 68'minutes
- 17MurrayBooked at 53mins
- Andy Madley
- Shots on Target
Second Half ends, Lincoln City 3, Brighton and Hove Albion 1.
Substitution, Lincoln City. Jamie McCombe replaces Alan Power.
Glenn Murray (Brighton and Hove Albion) wins a free kick in the attacking half.
Foul by Sam Habergham (Lincoln City).
Steve Sidwell (Brighton and Hove Albion) wins a free kick in the defensive half.
Foul by Terry Hawkridge (Lincoln City).
Attempt blocked. Nathan Arnold (Lincoln City) left footed shot from outside the box is blocked. Assisted by Sean Long with a headed pass.
Attempt missed. Tomer Hemed (Brighton and Hove Albion) right footed shot from outside the box is too high. Assisted by Solly March.
Connor Goldson (Brighton and Hove Albion) wins a free kick in the defensive half.
Foul by Jack Muldoon (Lincoln City).
Oliver Norwood (Brighton and Hove Albion) is shown the yellow card for a bad foul.
Foul by Oliver Norwood (Brighton and Hove Albion).
Jack Muldoon (Lincoln City) wins a free kick in the attacking half.
Attempt saved. Tomer Hemed (Brighton and Hove Albion) right footed shot from outside the box is saved in the bottom left corner. Assisted by Steve Sidwell.
Substitution, Lincoln City. Sean Long replaces Matt Rhead.
Attempt saved. Solly March (Brighton and Hove Albion) left footed shot from outside the box is saved in the bottom right corner.
Substitution, Lincoln City. Jack Muldoon replaces Theo Robinson.
Goal! Lincoln City 3, Brighton and Hove Albion 1. Theo Robinson (Lincoln City) right footed shot from the centre of the box to the bottom left corner. Assisted by Nathan Arnold.
Offside, Lincoln City. Bradley Wood tries a through ball, but Theo Robinson is caught offside.