It was a double save worthy of pretty much any superlative. Take your pick. Exceptional, outstanding, incomparable.

How David Raya denied Mateo Retegui not once, but twice, only he knows. It required every inch of his elasticity and was the difference between Arsenal leaving Italy with a point or nothing.

Not that they deserved much, their display hampered by a willingness to cede the ball to their opponents and struggle to get into attacking positions.

The striker struck his penalty to Raya’s right, and the Spaniard palmed it out with both hands.

The ball then rose in the air. Retegui had the whole goalframe to head it into. His header was a bit central, but that takes nothing away from Raya’s rapid leap up to scoop the ball off the line to his left-hand side.

It was the kind of reflexes you see in an action movie, not on a football pitch. The moves add to an astonishing double save against Aston Villa, and one against Wolves to deny Jorgen Strand Larsen’s headed effort.

The best goalkeeper in world football right now? He certainly is staking a claim for such a title.

Prior to pulling off his heroics, Raya had made his way to the touchline to converse with goalkeeping coach Inaki Cana, the VAR Jerome Brisard taking an age to deliberate on referee Clement Turpin’s decision. It worked, for sure.

The Retegui save was also a big let off for Partey, who gave the ball away on many an occasion. His foul on Ederson, grabbing the midfielder’s shirt before clinging on to his arm in desperation, summed up the Ghanaian’s night: chasing the game in its shadows.

A lacklustre start, then, to Arsenal’s Champions League campaign. They will need to be much, much better in their next continental games — and certainly against Manchester City this Sunday. Such a performance won’t suffice then.

The thought of being without Martin Odegaard, who faces a lengthy period out with a damaged ankle ligament, becomes even more of a concern.

The Norwegian’s work on the ball, cleverly piercing pockets of space, was needed here — but so was his pressing. Often, it his work off the ball that is a cog for the Gunners’ work in advanced areas.

After a six-season absence, Arsenal’s return to this competition in the last campaign had whet the appetite.

Watching compatriots Liverpool, Chelsea and Manchester City each lift the trophy in that period will have been tough. Though, reaching the quarter-finals of the Champions League against Bayern Munich in April was a marker. One to be surpassed next time around; the aim, anyway.

Arsenal were boosted by the return of Declan Rice from his domestic one-match suspension. It helped with an injury list including Mikel Merino, Oleksandr Zinchenko, Takehiro Tomiyasu and Kieran Tierney.

The season is still fresh. Further omissions are a worry with a jam-packed schedule. But, for now, they had to be focused and primed for Atalanta. The Italians are no mugs, their two Serie A losses thus far masking a team who have thrived and dominated in European football.

Their 3-1 aggregate victory over Liverpool in April’s Europa League quarter-final, before pummelling Bayer Leverkusen 3-0 in the final, had left Arsenal on high alert.

Particularly of Ademola Lookman, the man who struck those three against Leverkusen — the Germans hammered Feyenoord 4-0 in the Champions League last night.

Lookman never fully hit the grade in England with Everton, or on loan spells at Fulham and Leicester City but, in Italy, the 26-year-old has transformed himself, scoring 17 and providing 10 assists in 45 matches last season.

So much of a transformation, he made the Ballon d’Or 30-man shortlist this year.

There was also a reunion for ex-Gunner Sead Kolasinac, playing in the Atalanta back three.

Gabriel Jesus played the focal point up top, with Kai Havertz providing the aerial presence and physicality deeper in midfield.

The Gunners started on the front foot, mustering a series of shots at goal within the opening 15 minutes, including a wayward Bukayo Saka attempt. Havertz crept into the area on his weaker right foot, striking wide, before Saka was awarded a free-kick on the box’s edge, Ederson having pulled his shirt.

Saka cleverly struck it low, bobbling across the ground. Goalkeeper Marco Carnesecchi pulled off a great diving save to his right. It required a real wide stretch.

That proved to be the north London club’s best chance of the half, and those waves of attacks initially became stunted, Atalanta taking on the possession with Arsenal sat back.

Soon after, Retegui held off a defender to play through Charles De Ketelaere. His left-footed shot curled wide of the top-left corner. It was a reminder before the break of the home side’s danger with the ball.

The second half could not have started much worse after Partey’s tug on Ederson, with Raya left to bail him out with a stupendous double save.

Gabriel Martinelli had a great chance to win Arsenal the game, as he went through on goal after 77 minutes, only to shank the ball way over the goal.

Mikel Arteta was left with his head in hands. On this performance, you could not blame him.