Pierre-Emerick Aubameyang scored his second goal in an Arsenal shirt but that was scant consolation on a miserable day on the south coast.
We started brightly enough but the gloom descended when Shane Duffy beat Petr Cech to a deep corner to send a header back across goal, and Lewis Dunk poked in the loose ball.
It went from bad to worse when Laurent Koscielny gave possession away with a wayward pass out of defence. Brighton worked the ball to Pascal Gross and he crossed for Glenn Murray to bury a downward header.
Cech kept the score down with a vital stop from Anthony Knockaert but Brighton looked dangerous every time they came forward and were dominant in the air.
Things looked bleak, but we dug deep and grabbed a lifeline just before the break.
Alex Iwobi was first to a loose clearance and kept his head to pick out Granit Xhaka inside the box. The Swiss midfielder's driven low ball found Aubameyang, who stuck out a leg to flick the ball beyond Mathew Ryan.
We almost drew level before the break when Henrikh Mkhitaryan curled in an inviting cross and Duffy, under pressure from Koscielny, powered a header against his own post.
That was bad luck. Nonetheless, there was now an urgency and intensity about our play - and that continued after the break.
Mkhitaryan, Aubameyang and - most spectacularly - Ozil forced saves from Ryan as we forced Brighton back.
But the home side held firm to condemn us to a fourth straight defeat in all competitions.
WHAT IT MEANS
We’re in sixth place in the Premier League - 13 points behind fourth-placed Tottenham.
Our final chance of silverware is the Europa League and we head to the San Siro this week for the first leg of our last-16 clash with Milan.
CHANCES AT THE AMEX
Aubameyang scored his second goal for us since his record move from Borussia Dortmund. This is how close we came to a second goal on the south coast:
3 mins - Iwobi’s shot is blocked by a sliding Duffy, but Aubameyang seizes on the loose ball and finds Ozil for a curler that goes just over
40 - Mkhitaryan makes a run in behind the Brighton defence and Chambers finds him, but Ryan saves from a narrow angle
45 - Mkhitaryan’s corner is cleared back to him and his second cross is headed against the post by Duffy, under pressure from Koscielny
49 - Mkhitaryan takes aim from 20 yards out but Ryan gets down to save
51 - Iwobi finds space for a shot but he can’t get enough power on it and Ryan gathers comfortably
58 - Ozil surges through the centre, finds Aubameyang, collects the return pass and sends in a fierce shot that Ryan pushes around the post
89 - Wilshere has space on the edge of the area after a corner is half-cleared, but his shot bounces wide
90 - Aubameyang strikes a firm half-volley from 12 yards but Ryan is equal to it
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