Even the most optimistic Arsenal supporter would not have imagined things being so easy. Arsène Wenger’s side were defensively organised, tactically intelligent and ruthless up front, but their task was made significantly easier thanks to a bafflingly cavalier approach from Olympiakos.

Arsenal’s recovery complete after Olivier Giroud’s treble sinks Olympiakos Read more

The peculiar situation before this game – Olympiakos knowing they could lose and still progress – made things difficult for their coach, Marco Silva. In the build-up, he predictably insisted his players would play to win. “Never in any game, in any event, do we prepare to lose, and so we will not be doing that now,” he said.

Nevertheless, reports suggested Olympiakos would concede possession, soak up pressure and counterattack opportunistically. Nothing could have been further from the truth – Silva left his two wide players, Felipe Pardo and Sebá, high up the pitch against Arsenal’s full-backs, and pushed the midfielder Kostas Fortounis forward into a position where the visitors’ centre-backs, rather than central midfielders, were challenging him, while the full-backs charged forward.

In possession, it was 4-2-4 at times, and the transitions to a more defensive shape were barely noticeable, as Silva asked his midfielders to press. For the first 15 minutes, you could have been forgiven for thinking that the situation was the reverse – Olympiakos desperately needing the victory.

It was a peculiar strategy from a coach who has built a reputation as a fine tactician. In ordinary circumstances Arsenal do not enjoy playing against packed, solid defences; they love breaking into space. That is particularly true given the nature of this injury-hit side: the wide men – Joel Campbell and Theo Walcott – are pure speedsters, Mesut Özil is at his best when launching counterattacks, Aaron Ramsey is back in his favoured central midfield position and loves making lung-busting forward runs.

The exception, perhaps, was Olivier Giroud – the penalty-box poacher who lacks pace, so it was peculiar that the Frenchman would turn out to be Arsenal’s hat-trick hero. Still, Arsenal’s first two goals both originated from direct attacks. First, Ramsey sprinted down the left and delivered a fine near-post cross, which Giroud converted with significant help from the goalkeeper Roberto. Then, at the start of the second half, quick play found Arsenal breaking at three stranded Olympiakos defenders, with Campbell slipping the ball neatly through to Giroud who converted coolly. His hat-trick goal came from the penalty spot.

Olivier Giroud shows animal instinct to destroy Olympiakos with hat-trick Read more

Olympiakos’s approach played perfectly into Arsenal’s hands. Özil would have expected to spend this game collecting short passes from the central midfielders before attempting to slip a penetrative pass between eight opponents parked behind the ball. Instead, he received those passes on the run, drifting into pockets of space either side of Luka Milivojevic, his dream scenario.

Campbell and Walcott would have expected to be forced wide, stretching a compact defence determined to remain narrow. Instead, they were allowed to make dangerous runs between defenders and in behind, helped by Olympiakos’s two centre-backs sticking tight to Giroud when the Frenchman moved deep.

Arsenal had qualification secured with 20 minutes remaining. Before the game, Wenger might have worried about the imbalanced nature of his substitutes’ bench – he had an entire back four alongside him – but defensive options proved perfect for the latter stages, with Kieran Gibbs replacing Walcott as Arsenal protected their lead.

At 3-0, Arsenal showed Olympiakos what they should have done – two banks of four, the central midfielders remaining in position, the wingers breaking forward sporadically. Arsenal have often been eliminated from this competition through tactical naivety – here, it was a complete role reversal.