For Unai Emery this was an occasion to savour his work and question himself. The Arsenal manager quite rightly took delight in seeing his team maintain a perfect start to their Europa League campaign with a performance full of control and goals but it hardly did his reputation as a judge of talent much good that a player who struck twice and shone throughout as the spearhead of Arsenal’s attack is someone he does not feel has what it takes to be a central striker.

That was Emery’s assessment of Gabriel Martinelli before this game, with the Spaniard insisting the 18-year‑old, who joined Arsenal from Brazilian side Ituano in the summer, is better deployed in wide areas. That appeared far from the case when Martinelli tore Standard Liège to bits in that very role.

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His goals, which arrived inside three first-half minutes, were expertly taken and he continued to show impressive movement, poise and purpose, as he did when also scoring twice against Nottingham Forest last month as the main man up front.

Arsenal’s recent history is littered with South Americans who have faded fast but Martinelli looks a genuine prospect, and a goalscoring one at that.

Somewhat remarkably, Emery insisted again that central striker is not Martinelli’s best position but, having deployed him there, he went on to praise the teenager’s contribution, which alongside two goals included the assist for Arsenal’s fourth goal, a lofted cross that was turned into an empty net by Dani Ceballos on 57 minutes. “His performance and attitude was amazing,” said Emery. He was not wrong.

Facebook Twitter Pinterest Gabriel Martinelli runs to the fans after scoring the opening goal. Photograph: Andy Rain/EPA

Martinelli was just one of many players in red and white who caught the eye. Emery made 10 changes to the team that drew 1-1 with Manchester United on Monday and such was the hosts’ collective swagger and authority that you could forgive the man in charge if he decided to go with the same lineup for Bournemouth’s visit here on Sunday.

It is certainly possible that Héctor Bellerín, who captained Arsenal in his first start since January, will keep his place, as could Kieran Tierney, who was a dynamic presence at left-back in his second appearance for the club. Then there were the contributions of Reiss Nelson and Joe Willock, two more youngsters who yet again showed they have bright futures at the club.

The same can not be said for Mesut Özil who, as was the case at Old Trafford, failed to make even Arsenal’s bench. That is an ongoing saga that mattered little as Arsenal’s alternatives made their presence felt on the European stage for a second successive game. Last month’s 3-0 victory at Eintracht Frankfurt was followed by this thumping win and with two games gone, Arsenal already look primed to qualify with ease from Group F.

This should have been a test. Liège arrived here having won four of their past six games in all competitions and with a reputation for being a side full of technical quality. But they were lucky to leave here having lost only 4-0. “[Arsenal] were too quick for us for us,” said their manager, Michel Preud’homme.

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Arsenal were indeed quick, not only in the tempo of their play but also in how they built their lead. Three goals were scored inside the opening 22 minutes, with Martinelli getting his first on 13 minutes via a perfectly timed glancing header from Tierney’s near-post cross. The Brazilian’s second came from practically the same spot, this time via a composed right-foot finish, and entered him into Arsenal’s record books; at 18 years and 107 days he is the youngest player to have scored two goals in a major European game for the club.

Martinelli should have completed his hat-trick on 53 minutes but directed a low shot from in front of a practically open net wide of the far post.

In the grand scheme of things it did not matter – by that stage the hosts were rampant having gone 3-0 ahead thanks to Willock’s cool finish. Then came Ceballos’s goal, his first for Arsenal since arriving from Real Madrid on loan.