Last Updated: 06/11/13 10:56pm
THAT'S IT. What a result for the Gunners. Stick with us for report and reaction on an incredible night for Arsenal.
Lewandowski goes to ground appealing for a penalty but the referee waves it away. Is that the last chance? Mertesacker certainly had a hand on the striker.
Whistles from around the ground as Rosicky wins the ball in a challenge with Lewandowski. Looked hard but fair.
Koscielny back onto the field as Arsenal defend for their lives with Ramsey filling in at centre back.
Koscielny is taken out by Weidenfeller who gets nowhere near the ball. Surely there had to be a claim for a penalty. The keeper got nowhere near the ball. The defender looks in trouble here. He took a real whack.
Ozil again looking to hang onto the ball. What we have, we hold is Arsenal's motto as we enter the final few minutes.
Changes for Dortmund as the pacy Aubameyang comes on for Blaszczykowski while Bender makes way for Hofmann.
Bit of keep ball from the Gunners as they look to take the sting out of the hosts. Ozil becoming more influential after an incredibly quiet first half.
Frustration building on the terraces as Lewandowski tries to find Mkhitaryan. The Germans look a little rattled. Not often they find themselves behind on home turf.
Mertesacker comes close to doubling the lead but his header lands on the roof of the net with Weidenfeller nowhere.
Ozil and Cazorla are coming more into this game. A little more patience and they may find a way through.
Lewandowski goes down in the box as Arteta challenges him. Spectacular fall from the Pole but nothing doing from the referee.
And another Arsenal opportunity but Koscielny's effort is cleared off the line then Mertesacker just misses Ozil's centre.
Great chance for Arsenal to double their lead but Ramsey is denied - somewhat fortuitously - by Weidenfeller.
Reus misses from five yards out. Great cross from Lewandowski but the German international totally fluffs his lines from close range. What a let off.
ARSENAL LEAD. Incredible. Ramsey bundles the ball over the line with his head after Giroud flicks on Ozil's centre. The three have scarcely been in the game. What a moment for the Gunners.
Another foul from Arteta, this time on Lewandowski. One more infringement and the Spaniard will surely get a second yellow.
Dortmund have the ball in the net after more great play from Lewandowski but the assistant's flag saves the visitors. They are having to repel wave after wave of yellow attacks.
Good chance for Reus who gets good downward header from 15 yards which Szczesny does well to turn behind for a corner. The flag kick comes out to Mkhitaryan who fires over.
Alan Smith on Sky Sports commentary remarks that Ozil has been a peripheral figure in his home country - and that's certainly the case tonight. He's had very little influence.
We're back - and a worrying stat for the visitors is Dortmund have scored in 59 of their last 60 home games. Gulp.
Stats confirm not a single Arsenal shot in that first half - but incredibly they have had 53% possession. It certainly did not feel that way in the first period.
That's the interval. No goals and no chances for the visitors - but at least they go in level. If you want to get in touch with your thoughts on that first half you can. Get in touch via Twitter - @skysportswebed - or email@example.com
Arsene Wenger will be delighted to go in at half-time goalless. It has been a backs-to-the-wall effort.
Arsenal have not been able to get their passing flowing at all so far. Giroud has looked isolated while Cazorla and the talismanic Ramsey have scarcely been in the game.
What a golden chance for the Germans but Mkhitaryan shins it wide after Lewandowski broke clear of Koscielny. Germans should be one up.
Arteta tangles with Lewandowski. The Gunners midfielder needs to be careful here or he could be seeing red.
Mertesacker is at it again, this time to deny Lewandowski after a fabulous run and cross by Blaszczykowski.
More great defending from Mertesacker as Reus marauds forward. Superb play from the giant German to dispossess his international teammate.
Reus tangles with Rosicky. Arsenal are looking for a yellow card but nothing doing from the Dutch referee. As Arteta protests, we're treated to a bit of Bonnie Tyler from the home fans. It's A Heartache reverberates around the ground. That's one for the older fans among you.
At the other end, Ozil looks to advance but he can't quite get the ball out of his feet and is dispossessed.
Great defending by Koscielny as Mkhitaryan bursts into the Arsenal box. The Germans are beginning to look dangerous.
Giroud finally gets a tiny bit of space but he's penalised for the slightest of pushes. Looks a hard decision on the Frenchman.
Arteta concedes a free-kick which is swung in by Reus. Ramsey mis-directs his header back into the Arsenal danger area and Subotic swings his right boot at the bobbling ball which sneaks narrowly past the post.
Finally some pressure for Arsenal who force a corner which Ozil takes short then flings in a cross which is punched away by Weidenfeller.
The Gunners are on the back foot here. Bender drives at the heart of the Arsenal defence but Koscielny stands firm.
It's all very congested in midfield. Arsenal's passing will have to be at its most incisive to cut a way through the Germans.
Gibbs is out-muscled and Reus finds Lewandowski in the area but his threat is snuffed out by Mertesacker who had to move quickly to tidy up.
Rosicky wins the ball and drives forward to the edge of the box. He tries to clip it into Ozil but his chip is over-hit.
The atmosphere is building now. What a wonderful stadium this is. Here's some more feedback from Chris who says: "Coming to Signal Iduna Park can be a daunting task for any team, and I don't think Arsenal's players will find it easy if the atmosphere lives to expectations this evening. I expect the Gunners to win this one and get revenge on their opponents for what happened at the Emirates last month. Obviously, this won't be an easy match for the gunners, but their form has been stunning of recent, and if can produce another positive performance, they should have a good chance of claiming all 3 points."
It's pouring down in Dortmund - and has been for much of the day. The ball will skip off the surface so it should suit Arsenal's quick passing game down to the ground.
More from Twitter and @MattydBWFC says: "Neutral fan here! I can see Arsenal putting up a real fight tonight, I can see 1-1, Giroud and Reus with the goals!"
Fifteen minutes to get your thoughts and pre-match predictions in. Get in touch via Twitter - @skysportswebed - or firstname.lastname@example.org
Arsene Wenger has been talking to Sky Sports ahead of the game and says: "We had a bad start in the first game and they had one shot on target in the second which was the goal. This time we will start stronger."
Quick plug for our Events Centre. If you're a Sky Sports subscriber it's a great way to follow the match online with match stats, highlights etc. If not, then hopefully you'll stick with me.
Krishanu tweets: "@skysportswebed Arsenal will miss the steel in the middle of the park without flamini & wilshere, but ramsey & arteta would do just fine."
Thanks to @donkevz who tweets: "@Skysportswebed An early goal for Arsenal will really unsettle Borrisia Dortmund, this can cause the Gunner to win this match #Gunners."
So what do you think of the line-ups? Will Arsenal miss Wilshere and Flamini? Get in touch via Twitter - @skysportswebed - or email@example.com
Quick Twitter mention from the injured Jack Wilshere who tweets: "I'm sat at home waiting for the game to come on. Is quite possibly the worst feeling ever! Wish I was there! Anyway confident the lads will do it!" At least we know Jack's a Sky subscriber!
The Dortmund line-up has now come through: Weidenfeller, Grosskreutz, Subotic, Papastathopoulos, Schmelzer, Bender, Sahin, Kuba, Mkhitaryan, Reus, Lewandowski.
Matt's been in touch to say: "Huge test for Arsenal tonight. Dortmund are beatable though & an early Arsenal goal could unsettle them sufficiently. A point would be great though realistically & discipline will be key."
Here's the Arsenal side for tonight: Szczesny; Sagna, Mertesacker Koscielny, Gibbs; Ramsey, Arteta; Rosicky, Ozil, Cazorla; Giroud.
Before we get news of tonight's line-ups, time for a few fascinating Dortmund facts. 1: The Westfalenstadion boasts the largest standing area in Europe for domestic games. It has to be all-seated for European nights though. 2:You can buy a season ticket for 240 euros, which includes all Champions League home games. 3: Manager Jurgen Klopp is so tall he has to stoop when he walks through the tunnel and onto the pitch.
Still awaiting news of the teams but another prediction from Anthony who says: "I am a massive Gooner and think we need another big performance from Cazorla." Anthony is going against the odds with a 2-1 win for the visitors. Get your money on that then my friend. Sky Bet are quoting 12/1.
Very early prediction through from Mamun - and it's an optimistic one. Mamun says: "Arsenal to win 2-0 with Giroud netting once and Aaron Ramsey also on target."
Arsenal are rank outsiders with Sky Bet to come away from Germany with a win. They're 7/2 to triumph while the odds on a draw are 100/30. There's an interesting price boost on first goalscorer though with Mesut Ozil now 14/1 from 10/1. Might have a bit of that myself.
Join me for live coverage of tonight's crucial Champions League encounter. If you've a pre-match prediction then please get in touch via Twitter - @skysportswebed - or via email firstname.lastname@example.org