The Gunners 4-1 win over the Turkish giants saw plenty of players impressing, and one in particular disappointing.
Wojciech Szczesny 4.5/10 - Arsene Wenger will likely be furious with his young goalkeeper, who once again saw red in the Champions League. Though there are few doubting his ability as a shot stopper, moments like this are the reason the Arsenal boss invested in a top class alternative like David Ospina. Szczesny has to know when it is worth taking the kind of risk that got him sent off against Galatasaray, and when your side is coasting at 4-0 with 30 minutes left is not one of them.
Callum Chambers 7/10 - Another strong and assured performance from the 19-year-old, who looked a little more comfortable in a position he has played most of his professional football in.
Per Mertesacker 7/10 - A couple of difficult moments given the movement of the Galatasaray forwards, but tended to be able to position himself well enough to deal with the situation. Was caught out by the run for the penalty.
Laurent Koscielny 7/10 - Not completely fit and could have sat this game out such was the ease of the game for the first hour. Fairly untroubled for most of his time on the pitch.
Kieran Gibbs 7.5/10 - Possibly the strongest of the Arsenal back line, and looked really dangerous going forward down the left. Has to be a strong challenger for Leighton Baines England spot with this form.
Mathieu Flamini 6.5/10 - Vocal and energetic in the middle of the park, but lacking the quality of a genuine top class defensive midfielder and was booked.
Santi Cazorla 7/10 - He and Sanchez looked to link up well early on, though a little too much of a forward player to play one of the central midfield spots, especially in a tighter game. A couple of really skilful moments offensively.
Alex Oxlade-Chamberlain 8/10 - Full of confidence and energy after his equaliser in the North London Derby. Always eager to get involved and will be disappointed to have been substituted so early after being one of the opposition's chief tormentors. Created Welbeck's third with a super little through ball.
Alexis Sanchez 8/10 - Wenger may have found the perfect position to make use of the Chilean's frightening pace and skill, with Sanchez and Oxlade-Chamberlain shining on the wings. A menace all night, setting up Welbeck's opener and taking his own goal superbly.
Mesut Ozil 7/10 - Though the German looked leggy and tired throughout the game, he still managed to demonstrate his ability to pick his pass, as evidenced by his killer through ball for Sanchez's strike, which wiped the entire Gala defence out of the picture.
Danny Welbeck 9/10 - MOTM - Exhibited his pace and willingness to chase the opposition early on, managing to put Galatasaray players under decent pressure. Would go on to dispatch a trio of fantastic chances, each more accomplished than the last, and his confidence would have rocketed after his first professional hat trick.
David Ospina 62' 8/10 - The Colombian did excellent after coming in for the dismissed Szczesny, making several strong saves to stop any nerves which would have surely come had the Turks scored a second. Given his Polish teammate's indiscretion, could Wenger go with the former Nice goalkeeper as first choice in the near future?
Tomas Rosicky 68' 7/10 - Showed plenty of experience to settle the Arsenal midfield in what was a necessary change by Wenger once his side went down to 10 men. Still has a lot to offer at this level.
Jack Wilshere 77' 6/10 - Good for him to get some minutes after his knock against Spurs, linked up well though he was only on the pitch a few minutes and demonstrated an urgency and desire for the ball Ozil lacks.