The smallest of details brings the harshest of reckonings. There were two minutes left of added time and, given Arsenal had both a one-goal lead and unhindered possession of the ball, a tentative foot in the Europa League semi-finals was theirs. Cédric Soares received possession in the left-back position but, instead of looking upfield, checked backwards and handed responsibility to Gabriel. A heavy touch later and Jan Kuchta, a Slavia Prague substitute, had spooked Gabriel into slicing the ball off for a throw-in. Nineteen seconds after that Slavia had won a corner when Lukas Provod, their best player on the night, rattled the woodwork via Bernd Leno’s palms; a fraction over half a minute from there, Tomas Holes had powered in a header at the far post and Arsenal were left to wonder what would have happened if Soares had simply gone down the line. “We made a bad decision playing the ball into an area where we got trapped,” Mikel Arteta said. Inwardly, in those moments after the Czech champions plundered their away goal, he had been raging. Visibly and audibly, his players picked over the bones of the sequence that had allowed Slavia to build up such a devastating head of steam. Arsenal will now have to save their season the hard way, a defenestration in Prague next week almost certainly rendering the next month meaningless, and to say the song is wearyingly familiar would be an understatement. Put simply, they will get nowhere unless their moments of attacking brilliance are not cancelled out by sloppy decision making and a chronic inability to build on positions of strength. Their medium-term prospects are at stake and it is all the more maddening given there were passages here, albeit still too few in number, where it was just about plausible to envisage Pierre-Emerick Aubameyang lifting the trophy in Gdansk. Even if Arsenal do reach the final, though, there is no guarantee Aubameyang would start. Arteta demonstrated that here by dropping him for the second time in a month, anonymous performances against West Ham and Liverpool likely to be the cause this time, and it spoke volumes that they did not find a cutting edge until his 78th-minute arrival. Clear chances had been spurned and, while Slavia were competent in all departments and posed intermittent threats of their own, Arsenal should have opened up a lead. Aubameyang prodded wide from a decent position with virtually his first touch but seemed to justify Arteta’s gamble when, four minutes from the end of regulation time, he played his fellow substitute Nicolas Pépé through for a smart dinked finish over Ondrej Kolar. “It was a big decision to leave some players out but we decided to play the team that had the best chance to start the game and have key players to change the game when needed,” Arteta said. “They did what we expected them to do.” Nearly, but not quite. After Provod had seen that late rebound from the woodwork bundled behind, he swung a corner in towards the six-yard line and Pépé swiped a leg at the ball. But it flicked off his thigh and towards the far post, where the stand-in central defender Holes beat Soares to the ball and gave Leno no chance. What a regret that might prove to be, but there are others. Arsenal never quite coordinated their press or their possession play in the first half but should have scored when the otherwise outstanding Bukayo Saka broke the offside trap and slotted wide with time to pick his spot. Shortly after the hour, with Arsenal pushing hard by now, Alexandre Lacazette stole possession near halfway and had the entire Slavia half at his disposal. He ran through and sized up his finish but, with Kolar advancing, lifted his shot against the bar. Would Aubameyang have made sure? Between those two glaring opportunities, Willian had curled a 49th-minute free-kick against a post. “I think we merit more than the result we got,” Arteta said. “The game was under control. We got the goal we wanted but we missed some big chances as well.” Arsenal shoot themselves in the foot with such regularity, though, that it is difficult to know what they really deserve. Jan Boril and Petr Sevcik could both have given Slavia an outright lead during the second half; for all Arsenal knocked more insistently on the door after Arteta had flung on the cavalry, there was never quite a sense that their own was bolted shut. Then again, there rarely is. Arteta said the outcome “leaves a difficult taste”; a bitter end in seven days’ time would be even harder to swallow.