Match ends, Arsenal 1, Brighton and Hove Albion 1.
Arsenal's focus is now on the Europa League, says boss Unai Emery, after his lacklustre side's hopes of a top-four Premier League finish were effectively ended by a draw with Brighton.
The Gunners are three points behind Tottenham in fourth with one game to play but would need an eight-goal swing, as well as results going their way, to overtake their rivals.
Barring that highly improbable scenario, Arsenal will need to win the Europa League to play in the Champions League next season and take a 3-1 advantage into their semi-final second-leg in Valencia on Thursday.
"We knew it was going to be difficult but our focus is now the Europa League," Emery, who won the competition three times in a row with Sevilla, told BBC Sport.
"We have the opportunity in the Europa League to do something important and we will try and do that."
Pierre-Emerick Aubameyang put Arsenal in front at Emirates Stadium with a ninth-minute penalty after Alireza Jahanbakhsh was judged to have fouled Nacho Monreal despite appearing to get the ball.
Aside from occasional bursts, Emery's side were shaky and sloppy, with Granit Xhaka committing an absurd foul on Solly March to concede a penalty that Glenn Murray converted on 61 minutes.
Arsenal frantically searched for a winner but Aubameyang volleyed wide from seven yards out and Brighton keeper Mat Ryan made a series of fine saves.
Pascal Gross could have won the game for Brighton late on but skewed his effort out towards the sideline with the goal unmanned after Bernd Leno's superb save from March, while the visitors withstood another flurry from Arsenal in the final stages.
Sloppy Arsenal fail to scrape through
Looking to avoid a fourth straight Premier League defeat, Arsenal made a bright start in attack, though were fortunate to be awarded a penalty, despite referee Anthony Taylor being well placed, with replays showing Jahanbakhsh got to the ball before Monreal fell.
Still, an early lead through Aubameyang's 20th league goal of the season should have allowed the hosts to exert control over the game, but instead they became nervy and vulnerable.
Goalkeeper Leno sent an abysmal clearance straight to March before recovering to save Murray's free header moments later, while Stephan Litchtsteiner, making his first appearance since late February, was frequently exposed.
There was another promising spell at the end of the first half, with Aubameyang, Shkodran Mustafi and Henrikh Mkhitaryan testing Ryan, but Arsenal's inability to create clear chances gave Brighton increasing confidence in finding an equaliser.
Even then it took a staggeringly poor decision by Xhaka. Running behind the surging March inside the area, the Switzerland midfielder initially held up his hands to indicate he was not touching the Brighton forward only to then whack his shoulder and concede a penalty.
And so a game Arsenal should perhaps have dictated against an opposition who were already guaranteed Premier League survival became a manic attempt to salvage a dispiriting end to the league season.
They came close to scraping a winner but could not do it, the lap of honour conducted with glum faces as the Gunners must now focus on winning the club's first European trophy since 1994.
Safe Seagulls earn determined draw
Brighton's Premier League status was confirmed on Saturday when Cardiff were relegated following defeat by Crystal Palace.
But Chris Hughton's side looked determined not to let their season drift away, encouraged by Arsenal's defensive frailty.
March menaced Litchtsteiner, forced a save from Leno shortly after the break and made a fine run to win the penalty, perhaps going down easily but drawing contact from Xhaka, with Murray sending Leno the wrong way to score his 12th of the season.
Centre-backs Lewis Dunk and Shane Duffy made timely interventions and blocks, while Ryan continues to impress in goal.
With a more clinical edge, Brighton could have even won and completely ended Arsenal's top-four chances. First, Gross miscued his first-time strike after Leno had clawed away March's diving header in the 86th minute.
Then in added time, substitute Florin Andone oddly failed to look up and play in the onrushing March when Brighton had a two-on-one situation against the stretched Arsenal defence.
Man of the match - Solly March (Brighton)
'That is more like us' - reaction
Arsenal boss Unai Emery, speaking to BBC Sport: "We knew it was going to be difficult, but at 1-0 we needed to get the second goal. In the 90 minutes we controlled the match and after the first goal we tried to get the second.
"After their goal we created more chances to score but they defended very well, they are very strong defensively and they showed us that today."
Brighton boss Chris Hughton, speaking to BBC Sport: "That's more like us. It was a good reaction and a response to going a goal behind early in the game, people would have expected them to turn it into two or three. We had to dig deep.
"I was unhappy with the penalty decision, my feeling was that it was soft and I couldn't understand how he gave it. I saw it again and I haven't changed my mind. It wasn't a penalty, and a very poor decision.
"But we bounced back and showed a lot of character. Our responsibility is to try and get a result in every game - we will want to do as well as we can against Manchester City next week."
Brighton end 'big six' travel woes - stats
- Arsenal are winless in their last four Premier League games (D1 L3), their longest run without a victory in the competition since February 2016 (also four games).
- Brighton avoided defeat away from home against 'big six' opposition for the first time in the Premier League - they had lost each of their last 11 games before today.
- Arsenal have conceded 50 or more goals in consecutive top-flight campaigns for the first time since 1982-83 and 1983-84.
- Arsenal striker Pierre-Emerick Aubameyang is the sixth different player to score 20+ goals in a Premier League season for the club, and the first since Alexis Sanchez in 2016-17.
- Since making his debut in the competition in February 2018, only Mohamed Salah (35) has scored more Premier League goals than Aubameyang (30).
- Glenn Murray has scored 35% of Brighton's Premier League goals since the start of last season (24/68) - only Leicester's Jamie Vardy has netted a higher percentage of his team's goals in the competition in this period (36% - 38/107).
On the final day of the Premier League on Sunday, 12 May, Arsenal are away at Burnley, while Brighton host Manchester City, with both matches at 15:00 BST.
Before that, Arsenal face Valencia in the Europa League semi-final second leg on Thursday, leading 3-1 from the first leg.
- 12LichtsteinerBooked at 64minsSubstituted forKolasinacat 77'minutes
- 20MustafiBooked at 84mins
- 5PapastathopoulosBooked at 14mins
- 34XhakaBooked at 60minsSubstituted forIwobiat 77'minutes
- 7MkhitaryanSubstituted forGuendouziat 77'minutesBooked at 83mins
- 5DunkBooked at 63mins
- 16JahanbakhshSubstituted forKnockaertat 45'minutes
- 13GroßBooked at 45minsSubstituted forKayalat 90+2'minutes
- 17MurraySubstituted forAndoneat 78'minutes
- Anthony Taylor
- Shots on Target
Second Half ends, Arsenal 1, Brighton and Hove Albion 1.
Attempt blocked. Alexandre Lacazette (Arsenal) header from the centre of the box is blocked. Assisted by Mesut Özil with a cross.
Corner, Arsenal. Conceded by Yves Bissouma.
Attempt saved. Shkodran Mustafi (Arsenal) header from the centre of the box is saved in the bottom left corner.
Substitution, Brighton and Hove Albion. Beram Kayal replaces Pascal Groß.
Corner, Arsenal. Conceded by Solly March.
Attempt blocked. Alexandre Lacazette (Arsenal) left footed shot from the right side of the box is blocked. Assisted by Alex Iwobi.
Offside, Brighton and Hove Albion. Mat Ryan tries a through ball, but Anthony Knockaert is caught offside.
Attempt missed. Lucas Torreira (Arsenal) right footed shot from outside the box is too high. Assisted by Shkodran Mustafi.
Attempt missed. Alexandre Lacazette (Arsenal) header from the centre of the box misses to the left. Assisted by Pierre-Emerick Aubameyang with a cross following a fast break.
Offside, Brighton and Hove Albion. Anthony Knockaert tries a through ball, but Yves Bissouma is caught offside.
Attempt missed. Pascal Groß (Brighton and Hove Albion) right footed shot from the right side of the six yard box misses to the left.
Attempt saved. Solly March (Brighton and Hove Albion) header from the left side of the six yard box is saved in the top centre of the goal. Assisted by Pascal Groß.
Shkodran Mustafi (Arsenal) is shown the yellow card.
Attempt missed. Yves Bissouma (Brighton and Hove Albion) right footed shot from outside the box is high and wide to the right. Assisted by Shane Duffy.
Matteo Guendouzi (Arsenal) is shown the yellow card for hand ball.
Hand ball by Matteo Guendouzi (Arsenal).
Attempt missed. Bernardo (Brighton and Hove Albion) left footed shot from outside the box is close, but misses the top left corner. Assisted by Yves Bissouma.
Offside, Arsenal. Matteo Guendouzi tries a through ball, but Sead Kolasinac is caught offside.