The only two players with 100% pass completion on the field are Alex Iwobi and the irrepressible Cesar Azpilicueta.

Arsenal are edging possession but the Chelsea wall in front of them is very firm. Even as Iwobi stands over the ball there are two clear banks in front of him to beat. David Luiz and Gary Cahill protected by N'Golo Kante with distinction. 

As we tick over 40 minutes, Francis Coqeulin is the busiest man on the pitch with 43 touches. Pedro is Chelsea's go-to man with 34.

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Alex Iwobi advances down the left, he brings Nacho Monreal into play. The Spaniard crosses into the box and Gary Cahill shows excellent composure to chest back to his keeper.

Martin, Berks

Arsenal have now touched the ball in the area as they won a flick on from Nacho Monreal's corner. They win another one and work it short. In comes Francis Coquelin's delivery... MET BY GABRIEL... brilliant save. 

A one-handed claw away. Big chance, key save. 

If my contact lenses are accurate, Arsenal (right) have not yet touched the ball in the Chelsea area.

They have a corner though, won by Nacho Monreal.

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The fact three Arsenal players have just had to win headers in their final third tells you much about where the game is being played.

The fact those three players are Theo Walcott, Francis Coquelin and Alexis Sanchez hardly bodes well for Arsenal against this big and imposing side.

Chelsea have Eden Hazard and Marcos Alonso on the left flank, hence they are using that side of the pitch a great deal.

What's more, Hector Bellerin is off the field and Gabriel is probably now a target at right back.

Again Alonso gets forward to pick out Pedro in the box... parried save from Petr Cech.

Only one side looks like scoring the next goal. They wear blue.

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Danny Mills
Ex-England defender on Radio 5 live

Arsenal look a little bit shell-shocked at the moment, Chelsea are beginning to really take control of this game.

When Arsenal do have a spell with the ball they look vulnerable on the counter. Eden Hazard leads a charge and brings Diego Costa into the game but the big man gets his feet wrong near the area and gives the away defence a chance to intercept. Threat though. Plenty of threat.

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A little spell of Arsenal possession. Alex Oxlade-Chamberlain over the ball. He wants some shooting space but gets nothing than a Nemanja Matic wall smothering him.

"AAhhhh," yelps Nacho Monreal after a challenge from Victor Moses. Arsenal free-kick in a wide area... dire. Way too much on it, Thibaut Courtois gathers.

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Phil McNulty
BBC Sport chief football writer at Stamford Bridge

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Lots of debate here at Stamford Bridge about whether that was a foul by Marcos Alonso on Hector Bellerin for Chelsea's goal.

Personal opinion? Clearly a collision but that was a natural jumping movement from Alonso and not every collision is a foul...so correct decision for me.

Arsenal are creaking like an 18th century staircase. 

Eden Hazard teasing them down the left, drawing the odd "ole" from the crowd. His cross is superb to the back stick where Laurent Koscielny uses every inch to flick the ball clear.

We told you about this earlier. Thoughts? I can't believe they haven't got a Sam Dalla Bona one yet.

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This dead ball is in a dangerous area. Whipped in... in-swinger... headed away by Alex Oxlade-Chamberlain. Arsenal under it. They need to survive this next few minutes and go again.

Shkodran Mustafi with a humdinger of a challenge. Eden Hazard pushed the ball past him near the angle of the area so he just wiped his man out, no fuss.

Hazard limps away, Mustafi nods as if to say, "yep, I'll take that yellow ref".

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We have probably had an even start, as the stats suggest. The reality is though that the home side have just been a bit better with the ball when going forward.

Diego Costa's movement has been sharp, certainly when he found space for a key header leading to the goal.

Again he's quick into space now but the flag goes up against him.

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Ross, obviously an Arsenal fan.

No defender has scored more Premier League goals this season than Marcos Alonso's four.  

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Danny Mills
Ex-England defender on Radio 5 live

There is contact, but both players are coming for the ball.

I don't think it's a foul. Some people will say foul, some will say not. I'm pretty sure Alan Shearer wouldn't say it was a foul ,especially if it was him who scored the goal!