Match ends, Brighton and Hove Albion 3, Everton 2.
Lucas Digne scored a dramatic own goal in injury time at Brighton to consign Everton to their sixth defeat of the season.
In a topsy-turvy encounter, the 94th-minute goal, turned in from Leandro Trossard's cross, provoked jubilant scenes at Amex Stadium with Brighton goalkeeper Mat Ryan sprinting the length of the pitch to celebrate with his team-mates.
Pascal Gross had put the Seagulls ahead with a thunderbolt of a free-kick early in the first half, but Everton were level just minutes later through Adam Webster's own goal.
Substitute Dominic Calvert-Lewin scored within minutes of coming on to send Everton towards their first away win of the season.
But, just three minutes later, the video assistant referee (VAR) ruled Aaron Connolly had been fouled in the box by Michael Keane, Neal Maupay making no mistake from the penalty spot to level the score once again.
It was the first penalty awarded in the Premier League by VAR that the referee had not initially given, and Everton's frustrations were made even worse through captain Digne's mistake deep into added time.
The win was only Brighton's third of the season and seals successive home Premier League victories for the first time since October 2018.
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Despairing Toffees stunned by late comeback
Defeat will pile more pressure on the shoulders of Everton boss Marco Silva, who becomes the first manager to lose three Premier League games against Brighton.
The Toffees had ended a run of four straight defeats with victory over West Ham last weekend but if the future had looked brighter for Silva's men, that was soon dampened down in dismal conditions on the south coast.
Silva made one change for the trip to Brighton, with Mason Holgate coming in for the injured Yerry Mina for his first Premier League start in 13 months.
Little could separate the two sides in the early stages, but when Gross gave the hosts the lead, Everton responded in perfect fashion, Richarlison's header towards goal deflecting in off Webster.
That goal injected life into the Toffees - despite being forced into an early substitution when Bernard was injured off the ball - with Theo Walcott a constant thorn in Brighton's side.
Alex Iwobi went close to giving them the lead either side of the break, and after surviving a disallowed goal, Everton eventually took the lead in the 74th minute when Calvert-Lewin tucked the ball home with a composed finish.
But they were left stunned when Brighton were awarded a penalty after Keane appeared to step on Connolly's ankle, a challenge that went unnoticed by referee Andy Madley, who quickly found himself surrounded by Everton players when VAR gave the spot-kick.
Ten minutes of end-to-end action followed as both sides desperately searched for a winner, before six minutes of stoppage time was added, ending in despair for Silva's team as Digne slid the ball past his own goalkeeper.
Everton remain without a win at Brighton for 36 years.
Brighton's fortunes change
Three weeks have passed since Brighton stunned Tottenham but they were brought back down to earth with a bump last weekend with an injury-time defeat by Aston Villa. Seven days later, the tables turned.
Graham Potter's men struggled to settle in the opening exchanges of the match and it took 12 minutes for Amex Stadium to see its first shot of the day from either side.
But the hosts had the ball in the back of the net soon after, Gross firing a set-piece into the top corner for Brighton's first goal from a direct free-kick in the Premier League.
They managed to contain their visitors for the remainder of the first half after Everton's equaliser, and Steven Alzate - in for the suspended Aaron Mooy - went close to scoring early in the second, fizzing a shot over Jordan Pickford's bar after good play on the wing.
Just after the hour mark, Gross thought he had doubled his tally for the afternoon when he touched in a Davy Propper cross, but his strike was ruled out for offside, and it looked as though his side were going to be made to pay when Calvert-Lewin nudged Everton ahead.
But Maupay's easy finish from the spot brought new life into the game as tempers started to fray, with Trossard unlucky not to flick in from close range when a Lewis Dunk free-kick was unexpectedly punched into his path by Pickford.
Yet the Amex erupted when Brighton stole the win at the death, their first 90th-minute winning goal in their short Premier League history.
Man of the match - Steven Alzate (Brighton)
'My heart needs a rest' - what they said
Everton boss Marco Silva, speaking to BBC Match of the Day: "If VAR saw something in our box, why didn't it see 15 minutes earlier the penalty for Richarlison.
"Because of that my players are in the dressing room and don't understand.
"If they see one for one side then they have to see for the other side too. It was a clear penalty [to us]. VAR has to be the same for both sides."
On his side's late defeat: "We have to be more mature to control the last 10 minutes. It's a tough moment for us. We have to stick together.
"We conceded the first goal but after that we reacted strongly and as a team. We created some dangerous moments."
Brighton boss Graham Potter, also to Match of the Day: "My heart needs a bit of a rest after that!
"To turn it around like we did is an amazing feeling. It was an important moment to get the equaliser and there was a feeling in stadium for us to push on and get the win.
"I haven't seen replays of the penalty. We have had a few that have not gone our way recently. We have earned a bit of luck. We didn't play our best and it was a tough match. We had to dig deep."
- Everton have failed to win any of the 24 Premier League games in which they've fallen behind under Marco Silva (W0 D4 L20).
- The home side has never lost a Premier League meeting between Brighton and Everton (W4 D1), with Brighton winning twice and drawing once at the Amex.
- Lucas Digne's own goal was Brighton's first-ever 90th-minute winning goal in the Premier League.
- Dominic Calvert-Lewin has scored five goals in his last five appearances in all competitions for Everton, as many as he had netted in his previous 39.
- Everton netted their first set-piece goal of the 2019-20 Premier League campaign (via Webster's own goal) and their first since May 2019 vs Spurs (Tosun via a corner).
- Neal Maupay netted his fourth goal in 10 Premier League games for Brighton, twice as many as any other Seagulls player this season.
- Pascal Gross scored Brighton's first-ever direct free-kick in the Premier League and their first in league competition since Sebastien Pocognoli netted vs QPR in the Championship in April 2017.
Brighton welcome Norwich to the south coast on Saturday, 2 November, (15:00 GMT).
Everton host Watford in the EFL Cup fourth round on Tuesday (19:45 GMT) before Tottenham travel to Goodison Park on Sunday (16:30 GMT).
- 22MontoyaSubstituted forSchelottoat 65'minutes
- 24PröpperBooked at 90mins
- 6StephensBooked at 33mins
- 13GroßSubstituted forTrossardat 66'minutes
- 44ConnollySubstituted forMurrayat 80'minutes
- 2HolgateBooked at 86mins
- 21André Gomes
- 11WalcottSubstituted forDelphat 72'minutes
- 17IwobiSubstituted forCalvert-Lewinat 72'minutes
- 20BernardSubstituted forG Sigurdssonat 30'minutes
- 10G Sigurdsson
- Andy Madley
- Shots on Target
Second Half ends, Brighton and Hove Albion 3, Everton 2.
Own Goal by Lucas Digne, Everton. Brighton and Hove Albion 3, Everton 2.
Foul by Glenn Murray (Brighton and Hove Albion).
Mason Holgate (Everton) wins a free kick in the defensive half.
Davy Pröpper (Brighton and Hove Albion) is shown the yellow card for a bad foul.
Foul by Davy Pröpper (Brighton and Hove Albion).
Tom Davies (Everton) wins a free kick in the attacking half.
Neal Maupay (Brighton and Hove Albion) wins a free kick in the defensive half.
Foul by Lucas Digne (Everton).
Attempt saved. Lewis Dunk (Brighton and Hove Albion) right footed shot from outside the box is saved in the centre of the goal.
Mason Holgate (Everton) is shown the yellow card for a bad foul.
Neal Maupay (Brighton and Hove Albion) wins a free kick in the attacking half.
Foul by Mason Holgate (Everton).
Attempt saved. Steven Alzate (Brighton and Hove Albion) right footed shot from outside the box is saved in the centre of the goal. Assisted by Neal Maupay.
Goal! Brighton and Hove Albion 2, Everton 2. Neal Maupay (Brighton and Hove Albion) converts the penalty with a right footed shot to the top right corner.
Substitution, Brighton and Hove Albion. Glenn Murray replaces Aaron Connolly.
VAR Decision: Penalty Brighton and Hove Albion.
Penalty Brighton and Hove Albion. Aaron Connolly draws a foul in the penalty area.
Penalty conceded by Michael Keane (Everton) after a foul in the penalty area.