Robert Bach: If we don't get five, does that mean we are closer to Lincoln's level than Bayern's?

Chris Brown:  Was at Emirates on Tuesday for Bayern debacle and to be fair, fan situation was identical. Bayern and Lincoln fans magnificent.

Richard:  If Arsenal had as much heart against Bayern as Lincoln are showing today, they wouldn't have imploded so dramatically on Tuesday. 

Watch the goal that broke the back of this tie again below as Olivier Giroud steers in Arsenal's second.

Francis Coquelin is on for Arsenal now, Granit Xhaka making way in defensive midfield.  

It's just a case of how many now for the Gunners you feel. They are on their way to Wembley.

Mark Schwarzer
Ex-Fulham keeper on 5 live

Arsenal have lifted a gear and Lincoln have really struggled to go with them and that's what we expected. We expected a response from the last week or two and you feel a little bit sorry for Lincoln but we all expected Arsenal to do this and their quality should shine through in the end.

Image source, Reuters

A change from Lincoln as they try to freshen things up but in truth they are looking worn down now. This glorious cup run is approaching its end. 

Jonny Margetts is on for Jack Muldoon for the Imps, as Hector Bellerin bends a curling shot just wide of the post. So close to a third.  

Mark Schwarzer
Ex-Fulham keeper on 5 live

It was pretty easy for Arsenal in the end. We believed that Lincoln would have to weather storms for large parts of this game but they were too deep there. There were gaps in between and Giroud found one and it's an easy finish.

Image source, Reuters

Mark Schwarzer
Ex-Fulham keeper on 5 live

It was a good effort from Giroud. I thought he should have passed it to Sanchez who was free in the middle. Somehow it looks like Gibbs has just got too far underneath it and couldn't keep control of his header.

In three passes Arsenal are up the pitch and Olivier Giroud drives powerfully at goal from just inside the box. But it's a fantastic save from Paul Farman to palm the ball away, really strong hands to stop that. Down low, too.

It's played back across the net quickly, and Kieran Gibbs should do so much better with a header that goes sailing over the crossbar with Farman poised again.

Image source, Reuters

Mark Schwarzer
Ex-Fulham keeper on 5 live

Lincoln have done tremendously well. They've played with organisation and spirit and even put pressure on Arsenal with a decent chance to score. There's no great pace or passion for the hosts who are effectively just passing it around.

Alexis Sanchez has hardly had a say in this so far but here he is accidentally nutmegging his man, feeding Kieran Gibbs out wide and then fluffing his header on the cross that comes in. 

Mesut Ozil has a shot from range deflected behind but Lincoln can clear their lines from the corner. Back to Petr Cech it goes.

Alex Woodyard with a really badly timed challenge on Kieran Gibbs, he boots the Arsenal left-back up in the air. Agricultural with a capital A that. Yellow says the ref.

No changes for either side.

John Murray
5 live football correspondent

It's really strange to see this at the Emirates. The two sets of supporters can not be a greater contrast. The Lincoln supporters are vibrant and noisy on this great occasion, but the Arsenal section, where there are plenty of empty seats, are effectively sat on their hands.

Almost back under way at the Emirates. Lincoln are going to be shooting towards their 9,000 travelling fans this half. 

There is a woman in the crowd wearing a sign on her head that reads #Impvasion. 

Bob Moss: Arsenal with lucky goal, don't deserve to be ahead, Lincoln will regret missing that chance.

Dave Goodyear: Not unheard of for a team to score five in a second half at Arsenal.

James Ballantyne: Lincoln City putting up a better fight against superior opposition than Boro or Scotland today.

If you missed Theo Walcott's goal, watch again below. 

The England striker had earlier seen an effort tipped onto the post, but apart from that there's been very few chances to speak of for the home side. 

Lincoln are still in this - and they might have had a goal of their own through Nathan Arnold, only denied by Petr Cech's big glove behind.