The Gunners went down 4-0 there last month in a truly abject display which had all the usual criticisms levelled at Wenger and his men.

Too soft. Too predictable. Too short of real quality.

But they’re unbeaten in seven games since then and kept their fourth straight clean sheet in the league yesterday.

It was Nacho Monreal, with his first league goal in more than four years, and Alex Iwobi, with his first of the season, who scored the goals to see off strikerless Brighton.

But it was Alexis Sanchez who lit up the game, showing flashes of his brilliant best – and all with Mesut Ozil nowhere to be seen.

Ozil has played just 97 minutes of league football since the Liverpool disaster and is battling a knee injury. Without him, Arsenal are playing some of their best football.

Brighton caused problems in patches, and hit the woodwork too, but with on-loan Chelsea youngster Izzy Brown hardly getting a kick on his own up front, they never looked like troubling Arsenal.

So the Seagulls stayed two points above the bottom three, while Wenger was able to celebrate his 21st anniversary with his side’s fourth win in a row.

The Gunners had already hit the post through Alexandre Lacazette when Monreal gave them a 16th-minute lead by home through a forest of legs.

Jose Izquierdo, making his full league debut, had given away a needless free kick and Granit Xhaka swung it in for Alexandre Lacazette to head back into the danger zone.

Shane Duffy cleared the resulting shot from Shkodran Mustafi off the line, and Dale Stephens blocked the follow-up from Hector Bellerin.

But the ball rebounded out to Monreal who hit it first time on the volley into the bottom corner for his first goal since March 2013.

Did the ball go out of play before Lacazette headed it back in? Brighton certainly thought so, and Pascal Gross was booked for protesting too hard, but replays showed referee Kevin Friend got it right.

Brighton almost equalised soon afterwards when Solly March hit the post from 29 yards, with Duffy inches away from pouncing on the rebound.

But Arsenal should have had a second when Sanchez led a break which resulted in Sead Kolasinac squaring the ball for Aaron Ramsey, whose tame shot was straight at Mat Ryan.

They made up for it shortly after half time though. Sanchez, who had been trying to play Iwobi in all game, finally did so with a crafty backheel, and his team-mate couldn’t miss.

But the Chilean didn’t bother to join Iwobi in celebrating his strike, and that wasn’t the only time in the game his body language did not look good.

It was a tall order to expect Brighton to come back from that. Chris Hughton was in charge of the last newly-promoted team to win here, but that was Newcastle seven years ago.

They tried their best, and did at times look dangerous. But their lack of a finisher really showed.

Hughton failed to sign the striker he wanted on deadline day and with Tomer Hemed serving the first of a three-game ban for stamping on DeAndre Yedlin, they looked toothless.

Sanchez thought he had scored the third when he cut in from the left and beat Ryan with side-foot shot, but Lewis Dunk got just enough on it to deflect the ball just wide.

By the end Arsenal were worthy winners, and despite a late flurry from the visitors after Glenn Murray came on, Hughton’s side failed to manage a single meaningful shot on target.

At least the Brighton fans enjoyed themselves. They were still standing to sing and cheer them off when the Emirates had already half-emptied of home supporters.

Arsenal (3-4-3): Cech 6; Holding 6, Mustafi 6, Monreal 7; Bellerin 6, Xhaka 6 (Elneny 83), Ramsey 6, Kolasinac 6; Iwobi 7 (Walcott 71), Lacazette 6 (Giroud 71), SANCHEZ 8. Subs: Mertesacker, Wilshere, Ospina, Maitland-Niles.UP NEXT: Watford, (a) Premier League, Saturday October 14.

Brighton (4-5-1): Ryan 6; Bruno 6, Dunk 6, Duffy 6, Bong 6; MARCH 7 (Schelotto 72), Propper 6, Gross 6, Stephens 6, Izquierdo 5 (Knockaert 76); Brown 6 (Murray 76). Subs: Goldson, Krul, Suttner, Molumby.UP NEXT: Everton (h) Premier League, Sunday October 15

Referee: Kevin Friend 6Your turn: What was the scoreline when Arsenal last hosted Brighton in a league fixture?

STAR MAN: Alexis Sanchez – rejuvenatedSTAR SHOCKER: Jose Izquierdo – fatal errorsMatch: 3