Olivier Giroud
Olivier Giroud celebrates after scoring one of his three goals for Arsenal against Olympiakos. Reuters

Recap: Arsenal completed their great escape to qualify for the Champions League last 16 after Olivier Giroud grabbed his first hat-trick for the club in a 3-0 victory over Olympiakos in Greece. The prospect of getting out of the first group stage for a 16th successive season had appeared a distant one after Arsene Wenger’s side lost their opening two matches, including a 3-2 defeat at home to Olympiakos. And it was that result they needed to overturn at a hostile Karaiskakis Stadium.

They did so in impressive style, so much so that they could play out the remaining minutes in total comfort. That appeared an unlikely prospect at the start of the match, especially with Olympiakos, who now drop into the Europa League, beginning on the front foot. The Greek champions, who had needed just a single point front their final two matches to progress, caused an unbalanced Arsenal side real problems in the early going, as they counter-attacked with real purpose.

But it was Arsenal who were more clinical to get the vital opening goal. Mesut Özil supplied a fine through ball for Aaron Ramsey down the left and the Welshman’s cross was headed goalward by Giroud. With the ball going toward his near post, Olympiakos goalkeeper Roberto will be disappointed that he failed to keep it out, especially having got a glove to the effort.

Arsenal took a single-goal advantage into halftime and then grabbed a second to put them in the driving seat four minutes into the second period. Özil again played his part, but this time it was Joel Campbell who supplied a wonderful killer pass to pick out Giroud to drive low into the net. Campbell, who was going up against the club he played for on loan two seasons ago, was only playing because of Arsenal’s injury crisis, but he put on a superb display to suggest that he could yet have a real future at the Emirates Stadium.

It will be Giroud that grabs the headlines, though, thanks to his third goal midway through the second half. Omar Elabdellaoui handled Nacho Monreal’s drive in the box, giving Giroud the chance to fire home from the penalty spot. With the goal, his first treble in an Arsenal shirt and in the Champions League, Olympiakos were left needing to score three times. That was never going to happen, with Arsenal in complete control. The task now for Wenger’s side, having persevered one welcome Champions League streak, is to avoid continuing another and exiting at the Round of 16 for a sixth straight season.

Match highlights:

Olympiacos 0 - 3 Arsenal All Goals and Full... by ViralDailyTV

FULLTIME! Olympiakos 0-3 Arsenal
An Olivier Giroud hat-trick completes the great escape for Arsenal after losing their first two games in the group, and takes them into the last 16 for the 16th successive season. After a nervy start in Greece, it was a fine display from Wenger's men to in the end get the job done with a large degree of comfort. While Giroud will grab the headlines, with his first hat-trick for Arsenal, the performance of Joel Campbell, playing against the side he represented for a season on loan, was also exceptional.

92 mins: And now Giroud comes off to cheers from the Arsenal fans and boos from the home supporters. Calum Chambers is his replacement.

91 mins: Joel Campbell, who has been excellent tonight, gets a warm ovation from both sets of fans as he leaves the pitch, being replaced for the closing minutes by Alex Oxlade- Chamberlain.

89 mins: Not a lot happening in truth at a Karaiskakis Stadium that has fallen very quiet. Olympiakos briefly threatened, as Cech tips over a header toward his own goal from Koscileny. But, in truth, Olympiakos don’t look like getting one goal never mind htree.

83 mins: The game is well and truly up for Olympiakos and Arsenal are playing out the remaining minutes with a degree of comfort they would have found it hard to imagine at the start of the evening. It’s a massive disappointment for Olympiakos, who needed only a single point from their last two matches to qualify, but will have suffered big defeats against Bayern Munich and Arsenal.

77 mins: Seba, who was a threat early on, but has faded since, is taken off, replace by Hernani.

76 mins: Olympiakos are trying to push men forward, but they appear to have little conviction that they can get the three goals they need. Arsenal are now happy to sit back and play on the counter-attack. It’s surely a case of job very well done for the Gunners.

73 mins: Wenger makes his first substitution, bringing off Walcott, who isn’t yet fully fit, and bringing on Kieran Gibbs, who will sit in front of Monreal on the left.

Here's the penalty decision,a nd Giroud's third goal:

GOAL! Olympiakos 0-3 Arsenal (Giroud, 66)
Giroud completes his first Champions League hat-trick from the penalty spot and that surely sends Arsenal into the Champions League knockout phase. With goal difference in Arsenal’s favor, Olympiakos now need to score three times in order to progress at Arsenal’s expense. They were perhaps slightly unfortunate with the penalty, as Omar Elabdellaoui went to the turf in front of Monreal, only to see the ball strike his arm. But it was stretched far away from his body and it’s easy to see why a penalty was given.

Penalty to Arsenal!
Monreal’s low shot struck Elabdellaoui on the arm as he fell to the ground.

65 mins: Arsenal have relinquished the ascendency in the last few minutes, and Pajtim Kasami tests Cech once more with a shot from distance.

62 mins: Another anxious moment for Arsenal in their own box. This time it’s Brown Ideye who momentarily got free in the box, but his first touch let him down, allowing Arsenal to clear.

58 mins: But there’s a warning for Arsenal that Olympiakos aren’t done yet. Fortounis fires in a shot from 25 yards and Cech was at full stretch to turn it behind for a corner.

56 mins: It should be 3-0 for Arsenal. A cross from the right fell to Walcott at the far post, and he had the time to take a touch before firing a shot that was helped wide of the post. A third goal would be huge for Arsenal, given that it would leave Olympiakos needing to score three times.

Here's that goal from Giroud and the superb set-up play from Campbell:

GOAL! Olympiakos 0-2 Arsenal (Giroud, 49)
That’s an amazingly swift recovery from Giroud! Just moments after going down clutching his ankle, he fires in his second goal of the match to give Arsenal the scoreline they’re after. It was a fine pass helped forward by Ozil that set the move in motion, before Campbell did superbly to hold it up in the box and then pick out a pass through to Giroud who finished low on his left foot. As things stand, it’s Arsenal heading into the knockout phase and Olympiakos heading into the Europa League.

48 mins: Yet another injury scare for Arsenal. Giroud turned his ankle as he went to clear the ball, and the French striker went down in some pain. With the help of the physio he got back to his feet and off the pitch, and it looks like he will come back on.

47 mins: Olympiakos begin the half on the front foot, and Cech has to punch away a corner. It’s a tricky situation for the Greek side. They’re still in the driving seat, but another goal from Arsenal and they would be staring at the exit door.

Second half Kickoff! Olympiakos get the match back underway.

HALFTIME! Olympiakos 0-1 Arsenal
Wenger will surely have taken this scoreline at the interval. Arsenal have one of the goals they need, and now, providing Olympiakos don’t score, they just need to find the net once more in order to make it through to the last 16 of the Champions League. But it has been far from plain sailing for the visitors in Greece. Arsenal have taken plenty of chances pushing men forward and a more clinical side than Olympiakos would likely have already punished them. As it is, Arsenal have made more of their limited forward forays. After Flamini’s effort hit the bar, Giroud’s header beat Roberto, who should have kept it out at his near post. Arsenal are on track so far, but they have to be careful that Olympiakos don’t get a goal that would leave Wenger’s men needing to score twice more.

45 mins: Omar Elabdellaoui tires to become a hero with a thumping volley from all of 35 yards, but it sails well wide of Cech’s goal.

41 mins: Cech is called into action by a fierce shot from Arthur Masuaku, but the Arsenal goalkeeper holds onto it well.

40 mins: Danger for Arsenal. Pardo put in a really teasing ball right across the face of the six-yard box that was primed to be turned into the goal by Brown Ideye, before Laurent Koscielny stuck out a boot and sent it nervously over his own crossbar.

38 mins: The game has opened up far more now, which should favor Arsenal, as the team chasing a goal. Walcott just found space on the edge of the box, but dragged a poor shot wide of the post. Wenger would love a second goal before halftime.

Here's a video of that goal from Giroud:

GOAL! Olympiakos 0-1 Arsenal (Giroud, 29)
That’s the kick start Arsenal needed. Ozil played his part, feeding Ramsey down the left. The Welshman’s cross was perfect for Giroud, whose fierce header Roberto failed to keep out with his near post. In fact, it appeared as though the final touch was off the face of the Olympiakos goalkeeper, who probably should have done better. Arsenal now need just one more goal, providing Olympiakos don't score.

28 mins: Better signs from Arsenal in the last few minutes. A clever dinked pass from Ozil on the edge of the box almost found Olivier Giroud, but Roberto came out well to punch the ball to safety.

25 mins: Arsenal hit the crossbar! With the visitors’ first attack of any note, Campbell, now on the right, got free out wide and drove into the box before picking out the forward run of Flamini. But the Frenchman was off balance as he hit his shot and it deflected off a defender and against Roberto’s crossbar.

23 mins: Other than getting a goal, of course, Olympiakos manager Marco Silva couldn’t have wished for a better first quarter of this match. His side have been impressively compact without the ball, stopping the likes of Ozil from having any influence. With the ball they have given Arsenal some serious cause for concern and threatened to get a goal that would strengthen their position yet further.

20 mins: From another Olympiakos break, Felipe Pardo strikes over the bar. The move came down Arsenal’s left, where Walcott, who has just switched sides with Campbell, failed to track back.

18 mins: Aaron Ramsey enters the referee’s book for a late challenge from behind on Fortounis. Hard to argue with that one, and another sign of Arsenal’s struggles.

16 mins: Arsene Wenger has an anxious look on the sidelines, and with good reason. His side have not impressed so far. They’re struggling to get the ball into their danger men and when they lose it Olympiakos are posing a real threat.

12 mins: There already appears a clear plan from Olympiakos to try and hit Arsenal at pace down the flanks, where the attacking instincts of Walcott and Joel Campbell have left gaps to exploit. Brown Ideye just got in behind and through on Petr Cech down the right, but his cut back was cleared. It’s Olympiakos that look the most dangerous so far.

9 mins: Kostas Fortounis earns the first yellow card of the game after going to ground theatrically in the box trying to win a penalty off a challenge from Theo Walcott.

6 mins: Olympiakos troubled Arsenal on the counter attack in the match at the Emirates and they’ve already showed signs of being able to do the same tonight. It’s crucial for Arsenal that, while pushing for the goals they need, they retain their discipline defensively.

3 mins: A nervy start so far for Arsenal. Felipe Pardo, who scored at the Emirates earlier this season, looked to have gotten in behind the Arsenal defense but was flagged for offside before shooting over. It’s Olympiakos who have begun the brighter.

1 min: The atmosphere is certainly intense in Piraeus, with every one of Arsenal’s early touches being loudly booed.

KICKOFF! Arsenal get this crucial fixture underway.

2:42 p.m. EST: Wenger has just admitted to television that Theo Walcott isn’t fit enough to go for 90 minutes, and admits playing him is a risky decision. Players are now out on the pitch for the Champions League anthem. There had also been a doubt over the fitness of Mesut Ozil.

2:30 p.m. EST: With 15 minutes until kickoff in Greece, a look at the two teams. For Arsenal, Theo Walcott returns to the starting lineup for the first time since October, after coming off the bench against Sunderland on Saturday. Alex Oxlade-Chamberlain drops to the bench. Olympiakos, perhaps surprisingly, leave former Inter Milan and Leicester City midfielder Esteban Cambiasso on the bench.

Preview: For the fourth consecutive season Arsenal will go away from home in a decisive Champions League match, knowing that more than simply a victory will be needed to ensure progress. For the past three campaigns, Arsenal have gained creditable results, against Monaco and twice Bayern Munich, but ultimately crashed out, with the damage ultimately having been done at home. For manager Arsene Wenger, the task is to reverse that trend against Olympiakos on Wednesday.

A 3-2 defeat to the Greek champions at the Emirates Stadium in September left Arsenal playing catch up in their Champions League group. And it means going into the return fixture, Arsenal need to overturn that result, with either a victory by two goals or with a one-goal margin when scoring at least three times.

The reality is that if Arsenal come up short this time around, there will be even less glory in failure. While there has been frustration for Arsenal in bowing out of the Champions League at the Round of 16 for the past five seasons, an exit on Wednesday would mean Wenger failing to lead his side past the first group stage for the first time in 16 years.

Although Olympiakos have only ever made it to the Champions League quarterfinals once in their history, they have been no strangers to the knockout phase. The last time they were there was two seasons ago, when they bowed out to Manchester United, despite a 2-0 win in Greece helped by a goal from then on-loan Arsenal forward Joel Campbell.

The Costa Rican could well be involved against his former club in Piraeus on Wednesday. Arsenal have a long injury list, including Alexis Sanchez, Santi Cazorla, Francis Coquelin and Jack Wilshere. But Theo Walcott is back in contention after making his return off the bench in a 3-1 victory over Sunderland on Saturday. On the same day, Olympiakos earned a 4-3 victory over Panthrakikos to extend their winning start to the league season to 13 matches. They have also beaten Arsenal on all three of the sides’ previous meetings at the Karaiskakis Stadium.

Check back here from 2:45 p.m. EST for live score updates and video highlights from the decisive encounter.