In a contest between two thoroughly modern football sides, it was fitting that the major attacking outlets were not strikers, playmakers, wingers or central midfielders but instead full-backs. The quartet – Arsenal's Bacary Sagna and Kieran Gibbs, and Dortmund's Kevin Grosskreutz and Marcel Schmelzer, consistently had acres of space to exploit.
Everything about the shape of the game suited them. Both sides started with a high defensive line, compressing the play into a narrow band in the centre of the pitch, which meant the full-backs did not need to advance particularly far before they found themselves breaking past the opposition defensive line.
The match was played at a surprisingly slow tempo, despite a wave of heavy pressing from Dortmund in the opening minutes. It was rare for either side to attack directly; passing moves flowed at a gentle pace from defence to attack, giving plenty of opportunity for the full-backs to gradually ease forward down the outside.
With Arsène Wenger still lacking Theo Walcott, Lukas Podolski and Alex Oxlade-Chamberlain, and relying upon ball-players rather than sprinters in wide positions, Jack Wilshere and, in particular, Tomas Rosicky, flooded the centre quickly – again allowing the full-backs space.
Dortmund's system also contributed – Jürgen Klopp encouraged one of his central midfielders, generally Nuri Sahin, to drop into a deep position, allowing the centre-backs to spread and the full-backs to push on. The makeshift right-back Grosskreutz repeatedly found space in behind Rosicky, wastefully shooting twice early on, when he had opportunities to cross.
Therefore, this game was primarily about quality of delivery from wide positions.
Gibbs took advantage of his incredible acceleration to overlap consistently but his distribution was generally disappointing, whereas on the other flank Sagna had a couple of sighters before eventually playing a perfect cross between Dortmund's defence and goalkeeper, allowing Olivier Giroud to convert. Arsenal are not traditionally a side that profit regularly from crossing but the presence of an old-fashioned No9 makes this approach significantly more promising.
Still, the player allowed most space was Grosskreutz, the hard-working, unspectacular utility man. He positioned himself high up, his defensive duties partly covered by the central midfielder Sven Bender moving across, and looked to receive forward passes.
His energy over the course of the game was outstanding – he covered more than 11.5km – but his decision-making was frequently abysmal, best summed up by his hesitancy after 55 minutes when he surged past the Arsenal defence into a dangerous position, and produced a half-hearted, bobbling cross-shot into Wojciech Szczesny's arms.
Nevertheless, Dortmund needed only one good delivery from Grosskreutz and it came on 82 minutes: a fine driven cross was converted neatly at the far post by Robert Lewandowski, left completely unmarked on a counter-attack because Sagna's commitment to attacking left Arsenal bare down that flank. Arsenal can not say they were not warned. Wenger will be particularly frustrated to have been defeated in this manner – with Grosskreutz an unnatural right-back and Schmelzer playing his first match in a month, it was surprising that Dortmund's full-backs proved the difference.