Arsène Wenger is not, generally, given to reflection and it was no surprise when he gave only a grudging acknowledgement that this was the 21st anniversary of his appointment at Arsenal. But the manager did recall the moment towards the end of August when he waved his players off on the previous international break.

Back then, Wenger’s ears were ringing after the 4-0 humiliation at Liverpool while there was unease and uncertainty going into the final few days of the transfer window. “It was a nightmare,” he admitted. This time, there is tranquillity and positivity, and Wenger can luxuriate in the difference.

The 67-year-old is only ever one bad result from hearing the yells for his head but it never felt likely here, with his team in control from the first whistle. Were it not for some heroic defending from Shane Duffy and Lewis Dunk, the scoreline would have been heavier for Chris Hughton and Brighton.

Wenger rarely fluffs his lines against newly promoted teams. The last one to win at the Emirates was Hughton’s Newcastle United in 2010 and Arsenal strolled to these points thanks to only a second Premier League goal from Nacho Monreal and another from Alex Iwobi.

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Post-Liverpool, Arsenal have won three and drawn one in the league – and they have kept clean sheets on each occasion. Throw in a couple of Europa League victories and the mood is a world away from the hysteria that tracked the club from Anfield.

Brighton looked tidy, at times, and they finished with their heads up. The substitute Glenn Murray flashed a header past the near post and Davy Pröpper curled a shot just wide. But they never carried enough of a threat to make the game competitive.

Arsenal were nowhere near ruthless enough and it was tempting to wonder how many goals the Manchester clubs would have stuck away. Wenger lamented how his players’ focus was “a bit in and out” but it was not an afternoon to split too many hairs.

“I knew that after the game in Liverpool, everybody would write us off and I knew it just depends on us – how much we respond,” Wenger said. “Nothing is permanent. You’re not bad in a permanent way. You can do something about it.”

The home fans had rolled out of bed, yawned and sat back in expectation of a win. All the noise came from the Brighton hordes, who were magnificent, with those in red not inclined to extend themselves. They did not have long to wait for the opening goal.

Arsenal 2-0 Brighton & Hove Albion: Premier League – as it happened Read more

It followed a bout of pinball inside the Brighton penalty area, after Alexandre Lacazette had headed back Granit Xhaka’s free-kick from the byline beyond the far post. Brighton argued the ball had crossed the line. They were wrong. Shkodran Mustafi was the first to take a swipe and his shot was hacked off the line by Duffy. Héctor Bellerín then had an effort blocked and, when it spun up to Monreal, he controlled on his chest and lashed home.

Arsenal were comfortable, even if Brighton had a few flickers during the first half, none more eye-catching than the beautifully worked free-kick routine that finished with Solly March thumping in a left-footed shot from 20 yards that beat Petr Cech only to clatter into the upright. There was also the moment on 41 minutes when Cech flapped at a Pascal Gross corner, although Arsenal scrambled the ball clear and broke through Alexis Sánchez. Bellerín played in the overlapping Sead Kolasinac and he crossed low for Aaron Ramsey, who looked odds-on to score. Mathew Ryan, who was going the wrong way, stuck out a leg to keep out the shot.

Hughton had set up Brighton in a 4-5-1 formation and he wanted to keep the space in between the lines to a minimum. As usual, the key for him was discipline or, to put it another way, damage limitation. The approach did not become any more expansive after Monreal’s goal.

Lacazette looked dangerous, all explosive movement in the final third and slick technique. He hit a post in the second minute with a right-footed pop from outside the area, which had Ryan beaten, while he burst through on 33 minutes but finished weakly.

Iwobi had started in the continuing absence of Mesut Özil, who has a knee problem, and he would make the points safe. For the umpteenth time, Arsenal probed on the edge of the Brighton area, with Ramsey ever eager to make the run beyond the final defender. He gave the ball to Sánchez and went for the return, with the Chilean manipulating a cute back-heel that looked to be intended for him. It ran through, instead, for Iwobi and he planted his shot high past Ryan.

Iwobi had previously been denied on 13 minutes by the Brighton goalkeeper. The goal delighted Wenger, who has been keen to see greater productivity from him. “Players like him must score 10 goals and give between six and 10 assists,” Wenger said.

Arsenal were also without Laurent Koscielny because of a heel injury – Wenger expects he and Özil will be fit after the international break – but it was no real inconvenience. Sánchez was lively and he was denied a goal by a last-ditch intervention by Dunk while Kolasinac saw a header cleared off the line by March and Dunk denied Lacazette with a saving tackle.