Second-half goals from Julio Enciso, Deniz Undav and Pervis Estupinan earned the Seagulls a deserved victory at the Emirates that means Manchester City need one more win from their final three games to defend their crown.
City could be champions on Saturday night if Arsenal lose at Nottingham Forest with the gap between the top two now four points, and Pep Guardiola’s side holding a game in hand on the Gunners, who have failed to win five of their last seven matches.
“A really different feeling to the feeling that we all had last Sunday (at Newcastle) when we felt proud and we felt that we really did what we needed to win in certain moments. Today is completely the opposite,” Arteta admitted.
“We have to apologise to our people, especially for the second half.
“What I have to accept first is what happened in the second half and digest it.
“After that until it’s mathematically over… the second position is secure. That’s not going to change. We have to digest and that will take a few days.
“At the moment it’s just frustration. The feeling that we gave the game away in the second half. We fought really hard to be in the position that we are in and today we were in a critical moment to keeping hoping and digging for that dream.
“When you have to play in these moments you cannot do what we did in the second half.
“Then we have to look. If a team is capable of doing that when it comes to the biggest stage, there’s a lot of things to analyse and think about because it cannot happen.”
Gabriel Jesus tested Jason Steele midway through the opening 45 and Leandro Trossard clipped the crossbar with a swerving effort before Bukayo Saka dragged an effort wide from 14 yards at the end of a stop-start half.
Brighton punished Arsenal’s profligacy straight after half-time when Estupinan followed up his blocked cross with a scuffed centre that Enciso headed home for his third goal of the season.
Arteta made a raft of changes after but the visitors stayed in control and picked off the hosts with Undav able to lob Aaron Ramsdale in the 86th minute before Estupinan grabbed a deserved goal with a close-range finish in stoppage-time.
A reflective Arteta added: “Obviously what the team has done over the last 10 months is very different to what anybody expected and that generates a lot of expectation as well enthusiasm, happiness and joy.
“That’s something that has to be managed in the right way and after we have the responsibility to make sure the team performs and I am responsible for that.
“So, I hate the feeling of letting people down when they are expecting something. That’s the biggest regret I have today and I have to apologise for that.”
It was a different set of emotions for Brighton boss Roberto De Zerbi, who laughed off comparisons with Jose Mourinho after he wheeled off down the touchline to celebrate Undav’s goal.
He did insist, however, that nothing had been achieved by his sixth-placed side.
“Yes I am very delighted for the performances. I think we deserved to win but then really happy, really proud because the last five days were very difficult after the defeat on Monday (against Everton),” De Zerbi stated.
“We have 58 points and not enough to qualify for Europe.
“We have another four games, tough games, Newcastle, Southampton, City and last game Aston Villa and we have to fight to deserve to qualify because 58 points is not enough to play Thursdays next year.”