There was something inherently Arsenaly about the way Unai Emery’s team turned a 4-0 cruise so gentle Alexandre Lacazette was almost horizontal watching from the substitutes’ bench into a choppy, slightly unnerving finish. FC Vorskla, fifth in the Ukrainian Premier League, roused themselves to score two screamers in the closing stages of this Europa League group game, which left Emery pondering the defensive itch he is unable to scratch out of his squad yet. Arsenal have not kept a clean sheet all season.

This explains why it is so necessary to take the Europa League seriously. In their current defensive shape they do not look robust enough to easily regain a footing in the top four of the Premier League.

The late goals evidently took some sheen off an otherwise positive evening, which allowed Emery to give game time to experienced players in need of minutes and a chance to shine. Across the pitch were players keen to make an impact. Bernd Leno made his debut and impressed with his footwork but was understandably dismayed to twice pick the ball from his net after searing shots he could do little to repel. Lucas Torreira finally got a starting berth and showed why that ought to be a regular occurrence. Danny Welbeck snuck a goal. And Pierre-Emerick Aubameyang got his mojo back, which Arsenal will hope helps him into some serious form after an indifferent start to the campaign.

Due to a quirk in the rules so outmoded it has been abolished, Aubameyang was not allowed to play a single minute of Europa League football last season after his mid-season move from Borussia Dortmund to Arsenal. They needed him then, but he needed the Europa League now. The striker clearly enjoyed stretching his legs against the minnows from Poltava and scored twice to widen his smile.

Emery saw both the promising and worrying all in one game – not for the first time as he noted. Having felt the impact of late goals conceded against Chelsea and Newcastle, Arsenal exposed their own shortcomings when they switched off in the closing stages and that is a habit Emery wants to break.

“It is our disappointment today,” he said. “We need to improve in this. The last minute in Newcastle, the last 20 minutes here. Our challenge is to be competitive for 90 minutes in each match.”

If there were bits of the performance he wants to improve, he was certainly pleased with the result. Arsenal have won four matches in a row now, and getting off to a winning start in the Europa League was imperative.

It holds a special place in Emery’s heart given that he has won it three times, and although the path to the final in this competition is long, the Arsenal head coach took this opening group game seriously enough to pick a strong team.

Arsenal’s goals were smartly taken. The first arrived thanks to a counter-attack based on a welcome flash of pace and precision. Henrikh Mkhitaryan charged forward and picked out Alex Iwobi, who noticed Aubameyang switching on the afterburners. The Gabon striker, a surprise starter in this fixture, steered the ball across the keeper and into the far corner of the net.

After the break Arsenal could smell more goals. Mkhitaryan and Iwobi combined again and Welbeck timed his run to arrive in the right place at the right time to gently nod in a second. Vorskla were wilting, and Arsenal looked capable of carving open a chance at any moment. Aubameyang began to enjoy the space and another goal, crafted with a little help from his ally Mkhitaryan, was finished with curling finesse. Mesut Özil came on and helped himself to a fourth by deftly turning in Stephan Lichtsteiner’s cross.

But in the closing stages the section of Ukrainian supporters relished their team’s moment in the spotlight. Vorskla’s ambition at 4-0 down was creditable, and they were rewarded with a pair of goals to savour. Vlodymyr Chesnakov robbed Lichtsteiner to lash the ball ferociously past Leno, and in stoppage time Vyacheslav Sharpar ensured a double consolation with a rising drive in the last kick of the game.

“We are speaking before each match to take a mentality of don’t concede chances easily,” said Emery. “We needed to be better in the last 20 minutes.” It was a comfortable night’s work with a twist.