Olympiakos 0 Arsenal 3: five things we learnt as Gunners progress to Champions League Last-16

Giroud's hat-trick secured the treble for the Gunners

Mesut Özil (right) tussles with Manuel da Costa – the Arsenal player’s pass to set up the opening goal turned the night (EPA)

Giroud can now look Thierry Henry in the eye

On Arsenal’s pre-season in Singapore, Olivier Giroud was intensely irritated by having Thierry Henry’s comments that the club needed a top-quality striker continually repeated in front of him. This season he has given his reply with 13 goals, including a first hat-trick for Arsenal at a time they desperately needed it.

He has reflected Arsenal’s progress in the Champions League. He was sent off during the disastrous opening defeat by Dynamo Zagreb and was suspended for the capitulation at home to Olympiakos. But he came back to score a critical goal against Bayern Munich at the Emirates which gave Arsenal hope that their mission could be accomplished. He was absolutely clinical last night. His next encounter with Henry will be interesting.

Özil is the player that Wenger thought he was

After the uncertainty of his first two seasons, Mesut Özil is showing the touch that made him seem such a thrilling signing. He began this game with four goals and a dozen assists, and the pass that set up Giroud’s opening goal was effectively the ball that turned the night. The Greek champions’ confidence in their destiny began to crumble.

Özil remarked before this game that he never reads articles about himself any more but he might start wandering over to his newsagents after this display.

The Champions League group stage is working

Sometimes, as when Juventus reached the 2003 final having lost five matches en route, the Champions League seems vastly inferior to the magical simplicity of the old European Cup.

However, the last round of group matches show how well they can work. Manchester United’s fate flicked back and forth from the Volkswagen Arena to the Philips Stadion while Sevilla’s determination to reach a Europa League they have dominated ensured Juventus would not canter to the top of Group D.

Last night there was the straight, bare-knuckled fight in Athens – which felt like the second leg of an old European Cup fixture. At Stamford Bridge there were the kind of mathematical permutations Peter Snow would have relished while fronting the BBC’s election night coverage.

Arsenal’s wounds have been inflicted at home

For a second successive season Arsenal travelled to the northern shores of the Mediterranean trying to undo a disastrous result sustained in north London.

The 2-0 victory in Monaco last year was not enough to overturn the debacle at the Emirates, while the 3-2 defeat by Olympiakos in the autumn ensured the embarrassment Arsenal endured in Zagreb would become a crisis.

Between 2003 and 2012 Arsenal did not lose a single group game at home; since then defeats at the Emirates by Schalke and Borussia Dortmund and a 3-3 draw with Anderlecht ensured that while they might qualify for the knockout stages they would not do so in first place.

This was an escape at least as great as Liverpool’s

Their win in the Karaiskakis Stadium did not quite possess the late drama of Steven Gerrard’s goal at Anfield that took Liverpool through at Olympiakos’s expense 11 years ago.

Then, Rafa Benitez’s side were four minutes from elimination while Arsène Wenger’s could begin relaxing once Oliver Giroud completed his hat-trick in the 67th minute.

Nevertheless, Liverpool were never as out of contention as Arsenal were after two matches. The Gunners could only qualify by beating Bayern Munich and overcoming Olympiakos away in front of an intimidating crowd who had seen off the last half-dozen English sides to come here.

Liverpool went on to lift the European Cup in vastly improbable circumstances but Arsenal deserve immense credit. It may not match 26 May 1989 when they needed and got two goals to win the title but 9 December 2015 will be fondly remembered.