Dinamo almost doubled their lead at the start of the second half when El Arbi Soudani glanced a header against the far post, with the rebound scrambled behind.
It was 2-0 on 57 minutes when Fernandes got above three Arsenal defenders to head home a left-wing corner at the near post.
Wenger had seen enough, and soon made a triple substitution as Walcott, who once scored a hat trick for England in Zagreb, Francis Coquelin and Joel Campbell all came on.
Walcott reduced the deficit on 79 minutes when he produced a cool finish after sprinting clear onto Sanchez’s pass down the right, but there was to be no late drama despite some five minutes of added time.
TWEET OF THE MATCH
— Piers Morgan (@piersmorgan) September 16, 2015
ARSENAL PLAYER RATINGS
David Ospina: 5 (out of 10)
Mathieu Debuchy: 4
Laurent Koscielny: 4
Kieran Gibbs: 4
Alex Oxlade-Chamberlain: 6
Santi Cazorla: 5
Mikel Arteta: 4
Alexis Sanchez: 5
Mesut Ozil: 5
Olivier Giroud: 4
Theo Walcott: 7
Francis Coquelin: 5
Joel Campbell: 5
Junior Fernandes. The Chile forward was a handful for Arsenal’s defense all night with his pace and positive mindset. Showed great strength to leap through a crowded six-yard box and power home a header for the crucial second goal.
MOMENT OF THE MATCH
Having earlier seen two good chances missed, Giroud lost his cool to collect a needless second yellow card and leave his team up against it, chasing a match they should have already been in complete control of.
VIEW FROM THE BENCH
Dinamo manager Zoran Mamic had warned his side would not be sitting back against the Gunners, and despite riding their luck in the opening exchanges, the hosts grew in confidence to execute that positive game plan – helped in no small part by Arsenal’s inefficiencies at both ends of the pitch. Gunners boss Arsene Wenger, meanwhile, opted for half-a-dozen changes, aiming to freshen the starting XI up ahead of Saturday’s trip to Chelsea. But on this evidence, he will have plenty more adjustments to make to find the right balance again.
MOAN OF THE MATCH
Olivier Giroud should have known better than to trip Pinto when already on a yellow card. Whether or not either caution was soft, in the Champions League you cannot afford to give the referee a decision to make.