Brighton trail the league leaders at the Amex after a very early goal from Bukayo Saka when Albion failed to clear their lines.
Saka pounced on a loose ball after less than two minutes of play.
The Seagulls have had a few half chances to get back in it, with Leandro Trossard seeing Aaron Ramsdale make at routine save.
But although Brighton are enjoying plenty of possession, they have so far been unable to make it count.
Arsenal doubled their lead through Martin Odegaard about seven minutes before half time.
The Norwegian looped a shot over Robert Sanchez after Billy Gilmour headed a corner clear.
The game sprang to life just before half time, with Gilmour, Gabriel and Thomas Partey all receiving yellow cards for time wasting or fouls.
World Cup referee Anthony Taylor called both managers and all the interpreters together for a dressing down.
