We discuss five things that were learned from Arsenal victory over Borussia Dortmund last night.
Emiliano Martinez is capable
It is fair to say that a number of Arsenal fans were concerned when Wojciech Szczesny joined David Ospina on the treatment table.
The two experienced stoppers in Arsenal's ranks are both set for time on the sidelines, but Emiliano Martinez proved that he is capable of performing a role for the side.
The tall stopper may only be 19-years-old, but he is set for a good future in the game if he continues to perform to the standard he did against Dortmund last night.
Martinez pulled off a string of fine stops and should be proud of his display.
The England international has always looked a talent since arriving at the Emirates as an inexperienced teenager, but he is starting to look like the finished article now.
His display last night was full of menace and, at 21-years-old, he looks one of the brightest prospects in the country.
Sanchez can be an Arsenal legend
Alexis Sanchez's start to life at the Emirates Stadium has been nothing short of remarkable.
The Chilean continues to get better by the game for Arsenal and, without him, it is questionable just how poorly this campaign would have gone for Arsene Wenger's side.
He is undoubtedly the Gunners' finest player and, if he stays for long enough, is all set to become a legendary figure at the club.
Arteta a loss
Mikel Arteta may have his critics at Arsenal, but he proved last night he can still play a vital function for the side.
The 32-year-old is often exposed defensively, but he dictated the play last night before having to be substituted off with injury.
His calf problem is set to keep him out for six weeks and that could be a big problem for the side.
Sanogo may have some future
Yaya Sanogo may be very raw, but he does posses some talent and just needs moulding.
His display proved that he is capable of playing against the best, with his goal very confidently taken.
The French youth international may not be ready for a regular starting role, but if Wenger can show his ability to develop players Sanogo could become a weapon in the future.