Olympiacos 0-3 Arsenal Champions League RESULT: Olivier Giroud hat-trick puts Gunners into last 16 as Gunners run riot

Arsenal's Champions League campaign looked rocky after losing their first two games, but a remarkable fight-back sees the Gunners progress into the last 16 as group runners-up behind Bayern Munich.

There they join Manchester City and Chelsea from the Premier League, after the Blues also triumphed with ease over Porto (more full-time results here.)

Here are the last 16 teams in the Champions League: 

Real Madrid, Paris Saint-Germain, Wolfsburg, PSV Eindhoven, Atletico Madrid, Benfica, Manchester City, Juventus, Barcelona, Roma, Bayern Munich, Arsenal, Chelsea, Dynamo Kiev, Zenit and Gent.

Plenty of fall-out to come on the homepage but that's all from me here. Cheerio.

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Arsenal are through to the last 16 of the UEFA Champions League

90+2min: And a final change for Arsenal as Giroud departs in favour of Calum Chambers.

90+1min: There will be four added minutes as Campbell is given a standing ovation from everyone inside the ground (he once played for Olympiacos) as he is replaced by Alex Oxlade-Chamberlain.

89min: Cech is called into action but it's a routine stop from the Arsenal keeper who pushes over a defensive Koscielny header, which looked like it might've dipped under his crossbar, over.

86min: Final change from Olympiacos as Alfred Finnbogason replaces Pardo. That won't change the outcome of this game, much like the previous two substitutions.

85min: The atmosphere inside this ground was incredible before the game - how nearly 90 minutes of action changes things.

There are a fair few empty seats now, and like the Olympiacos team, the crowd have gone very flat.

82min: Ozil powers it towards the near post where Roberto rather curiously parries clear instead of taking a routine catch.

81min: Free-kick right on the corner of the Olympiacos box for Arsenal following a high foot. Ozil stands over...

80min: To think Giroud started this half with an ankle injury scare too. Mind yoiu he has gone down again after taking a knee in the back, but he will continue.

Here is a quick video showing his hat-trick:

77min: Second change for Olympiacos as Seaba departs in favour of Hernani. The hosts with all the ball but not much clue what to do with it. Arsenal remain comfortable at the back.

75min: Still 15 minutes to play but this game is over as a contest. If anything Arsenal will get the next goal as Giroud is only marginally offside trying to grab his fourth goal of the evening.

72min: Here comes the first Olympiacos change as Pajtim Kasami departs in favour of Alejandro Dominguez.

Arsenal follow with their own change as Walcott does indeed depart and Kieran Gibbs comes on.

70min: With 20 minutes to play, Olympiacos look shot - more shot than Walcott who I am surprised is still on the pitch.

In fact it's the home side looking to make changes.

67min: Job done. Olivier Giroud scores from the penalty spot to bag his hat-trick and effectively book the Gunners a spot in the last 16. Olympiacos need to now score THREE goals to deny Arsenal a Champions League future - not tonight, folks.

Omar Elabdellaoui blocks a low Nacho Monreal shot with his arm to give Arsenal a penalty. Good decision by the look of it.

63min: Giroud is booked for a late trip on Pardo, but I feel the latter's over reaction to the foul has got the Arsenal striker in the book there, as the hosts fumble a great opportunity to get a shot away inside the box.

61min: We are past the hour mark and given the scoreline, I wonder if Arsene Wenger will now be thinking now this is the time to bring off Walcott, who is not fit for the full 90 minutes.

Alex Oxlade-Chamberlain is on the bench and Olympiacos are still not showing much of a threat at all. Over to you Arsene...

58min: So nearly a third from Arsenal as Theo Walcott lashes just wide at the far post, but the home threat is still there as Fortounis cuts across the box before seeing a top corner bound shot well beaten away by Cech.

55min: So what should Arsenal do now? Attack of course. The Gunners must play to their strengths and a third goal, which they are more than capable of getting, would need Olympiacos needing to score THREE to progress at Arsene Wenger's team expense.

52min: It's not job done yet though for Arsenal, who qualify for the last 16 as it stands. Manual da Costa's point blank range header has plenty of power but is straight at Petr Cech.

49min: Continue? Never mind that - Olivier Giroud has scored again! Joel Campbell's through ball into the box has the Olympiacos defenders as still as statues, but not the striker who sprints into the area before poking home a low finish. His ankle - don't worry it looks fine!

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48min: Problems for Arsenal, big problems. Giroud has rolled his ankle trying to challenge for the ball and has gone down in agony.

After some treatment he is back to his feet, but will he be able to continue?

47min: Arsenal called into defending in the opening moments as Per Mertesacker nods clear under his own crossbar from a Pardo cross. Arsenal clear the corner.

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Mixed bag for the English so far. Chelsea lead Porto 1-0 which as it stands will see them top the group (follow that here with the rest of the action), but Gary Neville's first game in charge of Valencia sees them trail Lyon 1-0 at home (and you can follow that here.)

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He won't be credited with the assist, but Mesut Ozil's vision to spot Ramsey on the left which led to the goal was sublime.

The midfielder has popped up in attacking areas across the attack in the first half and you can bet he will be key if Arsenal are to get the one more goal they need.

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...ok, as it stands Arsenal are going out. But another half like that and the Gunners will be joining Bayern Munich in the last 16.

There's no reason ti think why they will not get the goal they need in the second half too. After a slow 20 minutes, the Gunners have settled rather well and you can be sure they will have many more chances to find that crucial second goal in the next 45 minutes.

44min: Olympiacos win a free-kick 40 yards out after Ramsey concedes a foul. This particular foul never warranted a yellow card, but the Arsenal midfielder is treading on egg shells having already picked up a booking earlier in this game.

Omar Elabdellaoui fires way off target from distance.

42min: And now a not so dangerous attack as Arthur Masuaku fires off target from the edge of the box.

40min: It's been a while since Olympiacos offered anything in the way of an attack but Pardo has come to life again, his dangerous cross from the right turned by Laurent Koscielny just over his crossbar.

Many of those sorts of interceptions can end up in the back of the net so brave defending from the Arsenal centre-back.

38min: The way this game has been going in the last 15 minutes I have little doubt Arsenal will get the job done this evening.

They are starting to really go at Olympiacos now as a clever Giroud run allows Theo Walcott space to run through the centre before the forward drags a low shot just wide.

35min: Arsenal are cranking up the pressure as they now win a corner, but the home fans' jeers soon seem to get the best of Ozil whose poor delivery is easily cleared.

32min: A once electric crowd have quietened down since that opener, along with the Olympiacos threat.

Right now all you can hear are the Gunners fans chanting Giroud's name. The hoem side look a little rattled.

29min: Now it gets interesting! Arsenal have the lead after Aaron Ramsey's cross is headed low by Olivier Giroud at the near post, with Roberto somehow letting it slip through his grasp as it creeps into the bottom corner.

As it stands Arsenal are still out, but one more and the gates to the last 16 open up before them...

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28min: And all of a sudden Arsenal are the better team. Mesut Ozil chips a lovely pass into the box but Roberto makes a brave decision to charge off his line and punch clear in front of a defender and Giroud

25min: There I go talking too early again. Two minutes later and Arsenal have the two best chances of the game!

Joel Campbell breaks down the right before cutting back for Mathieu Flamini, whose shot takes a deflection on the way to hitting the crossbar.

Moments later Giroud attacks a cross with a header but it's straight at Roberto in the Olympiacos goal. Much, much better from the Gunners.

23min: We are just about halfway through this opening 45 minutes and Arsenal haven't had a sniff on goal. Walcott, Ozil and Olivier Giroud have hardly had a kick between them.

The Gunners don't look too troubled in defence but in a game they must win this lack of attacking threat is a concern.

20min: Chance for Olympiacos. Pardo is giving Nacho Monreal plenty of problems on the right, cutting inside and seeing a shot blocked before a half-volley from 20 yards is struck just over the bar by Seba. He perhaps could have done better, but that's easy to say from behind a keyboard I guess.

18min: Still no shots for Arsenal but there are yellow cards as Aaron Ramsey hacks down Fortounis right in front of the referee to prevent a counter attack and 'collect one for the team.'

15min: If anything it's Olympiacos looking the more dangerous side right now. That doesn't say too much though, we have yet to have a shot on goal as Felipe Pardo over hits a cross past everyone inside the box from the right in a promising position.

12min: Credit to Olympiacos, they don't look like they are camped in for the night.

Seba releases Brown Ideye on the left, but his byline cut-back fails to find a team-mate as the Gunners hack clear.

9min: Top officiating. Kostas Fortounis takes a tumble inside the box, but with no Arsenal player going anywhere near him with a challenge, referee Nicola Rizzoli doesn't bottle it and books the midfielder for diving.

8min: Danger for Arsenal as they concede a free-kick out wide on the left after Hector Bellerin makes a rather needless foul on Seba.

6min: Arsenal have settled into the game and are controlling the possession as they press for an opener. Ozil and Walcott are shaping up well - the latter constantly looking to make runs in behind the defence.

3min: Every single Arsenal touch is being jeered in the early stages, with the Gunners already surviving one scare.

It came before the game though, with Mesut Ozil suffering a calf strain. The midfielder however came through the warm up without any problems and thus starts.

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The ground is absolutely packed as a red and white striped mosaic stretches across the entire section of home fans with a message in the centre reading 'We keep on dreaming.'

This match sold out in three hours and the atmosphere is a reflection of that - it's quite stunning, but can the Gunners silence them with a goal or two?

Olympiacos: Roberto, Elabdellaoui, da Costa, Siovas, Masuaku, Kasami, Milivojevic, Seba, Fortounis, Pardo, Ideye.
Subs: Kapino, Botia, Finnbogason, Dominguez, Salino, Hernani, Cambiasso.

Arsenal: Cech, Bellerin, Mertesacker, Koscielny, Monreal, Ramsey, Flamini, Walcott, Ozil, Campbell, Giroud.
Subs: Ospina, Debuchy, Gibbs, Gabriel, Oxlade-Chamberlain, Chambers, Iwobi.

Referee: Nicola Rizzoli (Italy)

'You want to be brave in a hostile atmosphere against a highly motivated team who are physically very strong,' Arsene Wenger told BT Sport.

'We need to be committed but disciplined and controlled and not get frustrated.

'I gave him [Theo Walcott] 30 minutes at the weekend and decided to start him today.

'I don't think he has 90 minutes, it's a bit risky but needed. We need to score goals.

'Certainly yes, it would be our greatest escape. But Olympiacos are an underrated team so we need to produce a top, top, top performance to escape tonight.'

Just in case you missed it earlier, Arsenal need to win by any margin other than 1-0 or 2-1 to progress this evening.

Failure to do so and it will be Olympiacos joining group winners Bayern Munich into the last 16.

It all goes down to a head-to-head record if the sides finish level on points, and Olympiacos defeated Arsenal 3-2 at the Emirates Stadium.

Should Arsenal win 3-2, they would progress on goal difference.

With Dinamo Zagreb guaranteed to finish bottom that means  if Arsenal fail to get the job done, they will be dropping into the Europa League.

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Theo Walcott's last start for Arsenal came in the home win against Bayern Munich - but it was a night where the forward didn't see much of the ball.

Mind you with just under 27 per cent of possession, not many Gunners players did - but it's telling that much of his contribution came from inside the Bayern box.

Olympiacos can't afford to let Walcott have that much play inside their penalty area - especially as the forward will want to be involved a lot more this evening. His pace will be key.

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It's all happening on the final night of group stage action. And here are all of this evening's fixtures.

Gary Neville takes charge of his first Valencia game when they face Lyon and you can follow all the action from that game with Sportsmail's Jack Gaughan.

Chelsea are looking to book a last 16 spot when they take on Porto and you can follow that game and the rest of the Champions League action including Barcelona with Sportsmail's Anthony Hay by clicking here.

Right here though - it's all about Arsenal vs Olympiacos.

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Theo Walcott hasn't started for Arsenal since their 2-0 win over Bayern Munich back in October but he returns from a calf injury as he replaces Alex Oxlade-Chamberlain in the only change from Saturday's 3-1 Premier League win against Sunderland.

Walcott was a second half substitute at the Emirates Stadium, but his return to the team provides a timely boost for an Arsenal side in need of goals this evening.

Olympiacos feature former West Brom striker Brown Ideye in attack while ex-Fulham midfielder Pajtim Kasami also lines up for the hosts.

Cech, Bellerin, Mertesacker, Koscielny, Monreal, Ramsey, Flamini, Ozil, Walcott, Campbell, Giroud.

SAMI MOKBEL: We've got ourselves into this mess; it's time to get ourselves out.

That's the message from Arsenal striker Olivier Giroud going into their date with destiny against Olympiacos.

Indeed, that, or something along those lines, should be the premise of Arsene Wenger's pre-match team-talk.

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Arsene Wenger's plan for Olympiacos on Wednesday night seems simple enough, with Olivier Giroud likely leading the line with Alex Oxlade-Chamberlain, Mesut Ozil and Theo Walcott in behind.

But the manager's doodling during the pre-match press conference could tell us there are more complex thoughts afoot, or that the Arsenal manager has other things on his mind ahead of the must-win Champions League group F finale.

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The stage is set in Piraeus where the home side only have to avoid defeat to progress to the last 16.

Take the red pill, and it's Thursday nights in the Europa League along with Manchester United who exited the Champions League yesterday.

But take the blue pill and it's a path to the last 16 along with Manchester City.

But enough of 'The Matrix' references. Good evening, all. Welcome to Sportsmail's live coverage of Arsenal's must win clash in Olympiacos.