The opportunity was there for Mikel Arteta’s side to extend their advantage after Manchester City were held by Everton earlier in the day, and the Gunners did just that against a Seagulls side that have regularly caused them problems in the past.
That always looked on track once Bukayo Saka gave them the lead after 65 seconds, before Martin Odegaard continued his sensational form to score before the break. Eddie Nketiah made it three shortly after half-time to seemingly put the Gunners in cruise control.
Kaoru Mitoma gave Brighton brief hope of a comeback though, before Evan Ferguson then did the same after Gabriel Martinelli had restored the three-goal advantage. Arsenal saw out the rest of the match, despite some unexpectedly nervy moments.
It means the Gunners go into the New Year with serious title ambitions, as improbable as that seemed even five months ago. Upcoming fixtures against Newcastle, Tottenham and Manchester United will likely prove to be a crucial run.
Barely a minute had been played by the time Saka put the Gunners in front, as he kept his nerve at the back post to finish with minimal fuss when the ball bobbled through to him.
Martinelli and Oleksandr Zinchenko had chances to swiftly double the lead, Arsenal threatening to run away with it as they made a sensational start on the south coast.
Brighton inevitably improved but did not fashion out much in the way of chances, and found themselves two down before the break. Saka’s corner was cleared out to Odegaard, who got enough on his slightly scuffed finish for it to bounce into the top corner.
Arsenal had to wait only a couple of minutes for their third goal after the restart, again flying out of the blocks. Robert Sanchez was unable to hold Martinelli’s left-footed strike and Nketiah was alive in the box to turn it home from close range.
Mitoma pulled one back for Brighton midway through the second-half, after a lovely ball from Pascal Gross, sparking hopes of a Brighton charge. Martinelli put a halt to that six minutes later, poking past Sanchez after a sublime pass from Odegaard had set him away.
Teenager Evan Ferguson got his first Premier League goal, after William Saliba failed to deal with a long ball forward, and Mitoma had the ball in the back of the net again late on as he cut inside and found the bottom corner. VAR ruled it out for offside though, and with that Brighton’s hopes came to an end.