Twenty minutes to go and, as it stands, Arsenal are heading to a February final date against Manchester City via a 2-1 aggregate win.

A Chelsea leveller would not send them through on away goals remember. Not yet anyway.

The away goals rule only comes into play after 30 minutes of extra time have been played.

Arsenal are not showing any signs of vertigo.

They are still pressing forward gamely despite being a goal up.

Granit Xhaka's 20-yarder trundles well wide. Not a good connection.

The former Chelsea man has got a point....

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Jermaine Jenas
Former Tottenham midfielder at Emirates Stadium

Mohamed Elneny is having a very strong second half. The decision from Arsene Wenger to drop him back 10 yards into defence is paying off. It's allowed Arsenal's creative players to do what they do best.

It was clear that Wenger needed to do something at half-time. Arsenal needed their fans behind them and you can see already what a difference it has made.

Wenger deserves credit for that tactical switch.

No fish-hooking or eye-gouging.

Nacho Monreal breaks one of the rules as he dishes out some UFC-style grappling to Eden Hazard and is slapped with a yellow card.

Up goes the signal. It's Bat-man time.

Pedro is called back to base and Michy Batshuayi - who Antonio Conte is willing to loan out if the Blues get a replacement in in January - is on in his place.

samkier: Good finish from Xhaka but those are two of the luckiest goals Arsenal will score all season! More goals in this one.

Bishaaj: Chelsea will come out now, defence please don't sleep

Snilloc94: Great awareness from Xhaka, but luck is not favouring Chelsea tonight! Is it going to be just 1 win in 8 Vs Arsenal (and Wenger) for Conte?

Victor Moses goes in two-footed on Alex Iwobi.

It is not at all pretty from the Chelsea man.

A yellow card decides Michael Oliver and the VAR boys back in the portacabin agree via a word in his earpiece.

Probably about right.

Jermaine Jenas
Former Tottenham midfielder at Emirates Stadium

Very, very good play from Alexandre Lacazette. He's been making these runs a lot with no joy but this time he is aware of Andreas Christensen and he is patient.

He waits to pick out his man and that is another huge slice of luck from Arsenal's point of view, the deflection off Rudiger into the path of Xhaka.

I have to say though, it's a great finish from Granit Xhaka!

Jermaine Jenas
Former Tottenham midfielder at Emirates Stadium

Eden Hazard and Ross Barkley are being very clever. Arsenal have got to watch them - too many times Hazard has been able to turn and get free.

He's got away with it too many times already.

The Arsenal fans strike up a chorus in praise of 'Super' Jack Wilshere.

The Gunners midfielder has just mistimed that pass to Alex Lacazette. Offside once again.

Image source, Getty Images

Chelsea have looked vulnerable to the ball over the top all night.

Mohamed Elneny scoops a pass over their high defensive line and into the path of Mesut Ozil.

Offside. But it was by a boot lace's width.

Edward Taylor: Arsenal fans booing Hazard are pathetic. It wasn't a dive. He just fell over and didn't appeal for anything. Nothing untoward at all.

Image source, Reuters

That could be a big call from referee Michael Oliver.

Eden Hazard gets goal-side of Shkodran Mustafi and is closing in on goal without any apparent defenders blocking his way.

Mustafi is desperately chasing after the Belgian and Hazard stumbles to the floor as the Arsenal man gets close.

All eyes on Oliver. Who decides it was a self-inflicted trip, rather than a foul.

There would have been a red-card question to answer if he had decided otherwise.

Image source, Reuters

Grant Xhaka has a set-piece to play with out on the right.

Decent, whipped delivery towards dangerman Nacho Monreal, but the visitors clear.

Jermaine Jenas
Former Tottenham midfielder at Emirates Stadium

I'm intrigued to see Mohamed Elneny's new position. Arsene Wenger may have decided to revert to a back three. I think it's a good decision - Alex Iwobi was getting held down by those defensive responsibilities.

Arsenal look to have switched away from the flat back-four they started with.

Image source, Reuters

Arsenal are dictating the early terms in the second.

Alex Iwobi flashes a stepover and briefly has Victor Moses chasing shadows. Cesar Azpilicueta steps in to lend a hand.

But Alexandre Lacazette wins the ball back again for Arsenal.

Eden Hazard attempts another dummy in midfield, allowing the ball to skim between his legs.

Nacho Monreal read it like a book though and pounces.

N'Golo Kante fouls the Spaniard, but Arsenal are on the front foot.

Granit Xhaka curls a shot over the top from 25 yards,

And we are go on the second half.

Plenty of fans still on their way back from the loos and food queues.