Mikel Arteta's Arsenal ran out 2-0 victors against Athletic Bilbao in their opening Champions League game of the season.
Gabriel Martinelli's second-half strike came merely seconds after his introduction from the bench, while Leandro Trossard's deflected effort secured the three points.
It was a classic Martinelli goal from the Brazilian. Linking up with fellow substitute Trossard, who flicked the ball on the halfway line, Martinelli touched it past the solitary defender with Bilbao's entire half ahead of him, but just the goalkeeper to beat.
And he did that with composure, sliding the ball underneath the diving Unai Simon. Trossard then grabbed his seventh Champions League goal after brilliant work from Martinelli in the box, with the Belgian's goal-bound effort deflecting over the despairing Bilbao goalkeeper.
The game also saw debuts for new Arsenal signings Christian Norgaard and Piero Hincapie.
With that being said, here are three things we learnt from the clash.
Mikel Arteta’s substitutions made the difference
Gabriel Martinelli's second-half strike came merely seconds after his introduction from the bench
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Mikel Arteta’s substitutions had an extraordinary impact on tonight’s game.
It took Martinelli merely seconds to get on the scoresheet after his introduction, while Trossard, who flicked the ball on for the opener and grabbed the second, had only been on the pitch for seven minutes.
While Viktor Gyokeres and Eberechi Eze were on the field, Arsenal looked like a threat. But when they were replaced by the aforementioned duo, it gave them a different route to attack their opponents.
Leandro Trossard's deflected effort secured the three points
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Martinelli’s goal was one that has been seen before from the Brazilian. His runs are always direct, trying to get in behind the opposition, which led to his opener - not something that is seen as often with Eze.
And then, as if the script had already been written, Martinelli set up the Belgian forward, whose deflected effort looped over Simon in the Bilbao net.
It is a clear sign that Arteta can impact games from the bench. He can influence matches, see what is in front of him and turn the game on its head. It is a great sign for the season ahead for the Gunners.
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Noni Madueke the danger man again
Noni Madueke shone throughout the game yet again
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Arsenal fans were almost despondent when they learned the news that they were signing Noni Madueke from Premier League rivals Chelsea for a fee in the region of £50million - they have changed their tune very quickly now.
What had been a decent, if not mediocre, spell at Stamford Bridge has suddenly transformed into an explosive and exciting start to life at the Gunners.
With Bukayo Saka currently injured, Madueke has taken his spot both at the Emirates and in the England side, and is giving a pretty strong argument to keep them.
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Against Bilbao, as was the case against Nottingham Forest and during the international break too, almost everything positive in an attacking sense came down his right side, particularly in the first half.
Granted, not everything he attempted came off, but it is his fearless running that strikes terror in defenders.
Crucially, he can go either way, inside and outside, leaving the defender simply no idea which direction to send him down.
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Noni Madueke is playing well enough for a permanent spot in Arsenal's starting 11
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Send him inside, and that puts him onto his stronger left foot, where he is capable of getting a decent effort on goal or, more likely, curling in a dangerous in-swinging delivery.
On the other hand, send him to the byline and he will likely put the ball past and find himself in an even more dangerous position in the box.
He has added a real threat to this Arsenal side this summer.
That’s not to say Eze hasn’t - he has looked bright and sharp - but Madueke will cause Arteta real selection headaches moving forward.
Bilbao a stern test for anybody
The atmosphere at the Estadio de San Mames was superb all night
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Athletic Bilbao always remains a tough test for any side facing them.
They are Spain’s fourth most successful club domestically and always put on a decent performance for the least.
Even though they were missing young starlet Nico Williams on the night, older brother Inaki led his side tremendously. His experience and importance to the team are clear.
The midfield of Mikel Vesga, Mikel Jauregizar and Oihan Sancet demonstrated brilliant flair and trickery and caused Arsenal some problems.
The result may not have gone they way they would have wanted, but they played their part in what was a thrilling encounter and forced Arsenal, who are a truly top team, to their bench for inspiration.
And the atmosphere at the Estadio de San Mames, which hosted the Europa League final earlier in the year that saw Tottenham defeat Manchester United 1-0, was rocking and set the scene for a fast-paced and enthralling match.
Newcastle, who host Bilbao in the first week of November, face a stern test. As do Paris Saint-Germain, who travel to the Estadio de San Mames on December 10.