What a chance! Chelsea so close to a leveller now as Branislav Ivanovic heads wide after an error from Iker Casillas.

Great game this. Riddles with errors at the back, but a great watch. 

Sixteen minutes left!

Chelsea need a lifeline and they throw on youngster Kenedy and Nemanja Matic to try and save themselves. Off go Pedro and Ramires. 

Plenty of passes in Alexis Sanchez's equaliser...

Image source, .

But, parity only lasted 59 seconds... 

Image source, .

Mark Lawrenson
BBC Radio 5 live in the Estadio do Dragao

Image source, Getty Images

  "Chelsea are defensively all over the place. What a noise that is coming from the home fans." 

Phil McNulty
BBC Sport chief football writer

"No need for three guesses what the mood is like inside The Emirates. Fury, frustration, disbelief. And more besides. Once again they have got themselves back into the game only to be opened up with ease by Olympiakos. The vulnerability has to be seen to be believed."

Pasa Mustafa: Where would we be without him. Alexis you beauty!

James Foster: Well that didn't last long...

Paul Hawkins: That, is Arsenal in a nutshell.

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There's drama at Adams Park as Cambridge goalie Chris Dunn is sent off for a foul on the last man against Wycombe, conceding a penalty in the process.

Sub keeper Sam Beasant comes off the bench to save the resulting spot-kick - certainly living up to his namesake. His save keeps it goalless. 

Accrington are 2-1 up against Yeovil, it's 1-1 between Leyton Orient and Carlisle, Plymouth are 2-1 up vs Barnet and Bristol Rovers have made it 2-0 at Hartlepool.

Mansfield are 2-0 up at Stevenage and Portsmouth are now losing 2-0 to Exeter. York and Oxford are level at 1-1.

Quite a last 20 minutes in store, in both games tonight. Asmir Begovic has his wrist bent back by a rasper from Giannelli Ibula! Good save.

Gary Cahill then has to scrabble over and make a goal-saving challenge. Chelsea's defence is beyond ragged. Riches to rags...

Mark Lawrenson
BBC Radio 5 live in the Estadio do Dragao

"To concede a goal so quickly after getting back into the game. That's Arsenal isn't it?"

Santi Cazorla with a 30-yard piledriver but it's easy for Roberto to push away. Arsenal look more dangerous since Aaron Ramsey entered the fray. 

Steven Jerijan: At this rate, England is going to lose that ‘better than a trophy' fourth Champions League spot faster than you can say “coefficient”.

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Last season Premier League sides lost six of 24 Champions League group games - if the results stay like this they will have already lost FIVE...

Subs don't get much more attacking than this. Eden Hazard on for Jon Mikel Obi.

Chelsea have 28 minutes to rescue this - and straight away Hazard hits the side-netting...

Phil McNulty
BBC Sport chief football writer

Arsenal struggling to make any openings here so far in the second half. The Emirates is subdued apart from one corner packed with noisy Olympiakos supporters. The pace of Theo Walcott has unsettled the Greeks when given the opportunity - Arsenal just need to get him into the game.

I told you to put him up front! Per Mertesacker has a shot well blocked and on the follow-up Santi Cazorla middles the shot, lovely connection, but it's headed clear off the line! Much more like it from Arsenal. 

Olympiakos are very much in shut-up-shop mode as the two heats map show below. (Olympiakos right, Arsenal left).

Image source, .

Aaron Ramsey now on for Arsenal who have yet to threaten in the second period. 

We have mentioned it many times before but they have to face Bayern Munich twice in this group still...