Liverpool vs Arsenal, five things we learned: Unai Emery's tactics open door for Mohamed Salah and co

A four-diamond-two formation was notable for its narrowness: designed, perhaps, to congest the centre but ignoring the reality that Andrew Robertson and Trent Alexander-Arnold are Europe’s most feared full-backs

EMERY’S NARROW APPROACH BACKFIRES

Jurgen Klopp has noticed how teams tend to experiment with tactics they have rarely used before at Anfield. Even he may have been surprised to encounter an Arsenal side without width. A four-diamond-two formation was notable for its narrowness: designed, perhaps, to congest the centre and prevent Liverpool from finding even the smallest of gaps in the areas where their midfielders and forwards combine in close quarters, but ignoring the reality that Andrew Robertson and Trent Alexander-Arnold are Europe’s most feared pair of attacking full-backs, men who got 23 Premier League assists between them last season and who were invariably afforded acres of room to cross. The predictable element was that Liverpool’s breakthrough would come with a centre from one of their full-backs. The only surprise was that it was from a corner when Alexander-Arnold picked out Joel Matip to head in. It was the 19th cross that the full-backs had delivered in the opening 41 minutes. It felt inevitable, just as it did when Liverpool’s second goal stemmed from an unmarked Alexander-Arnold’s pass to Roberto Firmino.

DAVID LUIZ ENDS UP LOOKING A LIABILITY

Sometimes it feels there is no middle ground where David Luiz is concerned. His best is very good. His worst is rotten and, because he is so conspicuous, there is no hiding place. At half-time, there was a case for arguing Luiz had excelled. A quarter of an hour into the second half, very different conclusions could be drawn. His duel with Mohamed Salah was a comprehensive victory for the Liverpool forward. David Luiz was twice caught out of position inside 10 minutes, tugging Salah back to concede a penalty and hurtling in, rather needlessly, when Salah met Fabinho’s pass and darted away from him to add Liverpool’s third goal. It showed more enthusiasm than judgement. It is scarcely the only moment in David Luiz’s career when that accusation can be levelled at him.

FIRMINO TROUBLES ARSENAL AGAIN

Firmino scored a hat-trick against Arsenal in last season’s 5-1 thrashing and has a status as their nemesis. Perhaps it is because he can seem their antithesis, the big-game player, the relentless runner, the selfless worker, the attacker who is also the first line of the defence. Perhaps it was fitting that, on a day when he could have drawn level with Ian Rush and Gordon Hodgson as Liverpool’s joint leading scorer against the Gunners, a selfless sidekick instead set up a goal. His pass for Salah, leading to the penalty when David Luiz fouled the Egyptian, was a trademark Firmino ball, only travelling a few yards, but finding an on-rushing colleague. Liverpool have inverted the front three, with Salah and Sadio Mane often in more advanced positions than Firmino, and it was an illustration of why the formation works and why, even as the Egyptian got the goals, the Brazilian is the man who makes the front three tick.

PEPE MISSES HIS CHANCE BUT SHOWS HIS SPEED

Exit Arsenal’s player of the year, enter their record signing. Not for the first time, Alexandre Lacazette was benched at Anfield as Nicolas Pepe made his maiden start for Arsenal. They received indications of what £72 million buys: blistering pace, most obviously, and a willingness to cut in from the right to shoot on his favoured left foot. They are, of course, traits he shares with Salah but if Pepe promised a first Gunners goal with a Salah-esque counter-attack, surging past Jordan Henderson and Robertson, his subsequent shot was too close to Adrian and allowed the Spaniard to save. Nevertheless, Pepe’s performance suggested he has the potential to torment defenders, especially when Lacazette is incorporated into a forward line with the newcomer and Pierre-Emerick Aubameyang.

Nicolas Pepe showed glimpses of his talent (Getty) (Arsenal FC via Getty Images)

ADRIAN OFFERS DRAMA EVERY GAME

There were times in Alisson’s first season at Anfield when he was a spectator. His understudy, Adrian, has only played four games in a Liverpool career that still is not three weeks old, but has been a central character in each. He has won Liverpool a trophy, with his shootout save from Tammy Abraham in Istanbul, and cost them a goal, gifted to Danny Ings at Southampton last week. There was almost another in the debit column: a stray kick allowed Aubameyang a chance and his lob dropped agonisingly wide of the empty net. If it points to an erraticism, it also offered a reminder that Alisson is excellent on the ball. His deputy has rather less safe feet and, after Lucas Torreira’s late goal, his quest for a clean sheet continues.