Olympiakos's opener could not have been simpler...

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It's the joy of six for Stanley: undefeated in their last six, Accrington are a goal ahead at home to Yeovil thanks to Josh Windass, who bags his sixth of the season.

Further south, Portsmouth's unbeaten run is in danger as Exeter are leading at Fratton Park. The Grecians knocked Pompey out of the League Cup exactly four weeks ago this evening - are they becoming bogey side for Portsmouth?

Luton have gone 2-1 up at Morecambe, Wimbledon are winning 1-0 against Northampton and Oxford are a goal to the good away at York.

Roman Taylor: Diego Costa is actually PLAYING a game of football, rather than trying to fight everyone!  

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Brown Ideye! Dear oh dear. Arsenal's centre-backs get in each other's way to give Brown a free hit on goal but he can't sort his feet out and is eventually crowded out. Corner.

Francis Edwards: Lucky enough to be at the Bayern v Zagreb game, how on earth did Arsenal lose to this team? Could be double figures tonight.

I think I know the answer to this one Frank. It's because Bayern are REALLY GOOD at football. Robert Lewandowski has just scored (again) to put Bayern 4-0 up now. That's his ninth goal in three games...

Lovely feet from Porto full-back Maxi Pereira to get a shot in which is deflected away. Pereira will be on the move to the Premier League or El Clasico soon enough. Most Porto defenders seem to eventually...

Mark Lawrenson
BBC Radio 5 live in the Estadio do Dragao

Image source, Reuters

"Diego Costa is head and shoulders above everyone else on the pitch so far in this game. He's been far and away the best player."

Plenty of touches for Chelsea striker Diego Costa but, so far, none inside the penalty area.

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Barcelona are behind! Kyriakos Papadopoulos has scored for Bayer Leverkusen (a real scrappy one at the near post from a corner) at the Nou Camp. Barca are without Lionel Messi, remember... Luis Suarez and Neymar to the rescue?

In the other game in Chelsea's group, Dynamo Kiev are leading Maccabi Tel Aviv 1-0, while in the other game in Arsenal's group, Bayern Munich are already 3-0 up at home to Dinamo Zagreb.

Vincent Aboubakar pins his man with a ball into feet, he rolls the defender and shoots high and wide over the bar. Porto then think they should have a penalty - Branislav Ivanovic gets the ball but he does dive in a bit. 

Anyone get the feeling Olympiakos believe they can get at Arsenal down the flanks? As the graphic shows below, the Greeks have hardly gone down the middle as an attacking force.

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Olympiakos have a rare foray forwards and Kostas Fortounis skims a left-footed strike wide from 20 yards. 

Devil's Advocate: I can't understand why Pep Guardiola is leading your poll. The teams he's managed practically pick themselves...

Stephen Broadbent: Can't believe Jose Mourinho and Arsene Wenger are close in the manager vote. How many titles has Jose won again?

There's still time to vote by the way, who would you most like to manage your club?

The heat maps below suggest Porto, left, are playing a little bit further forward than their visitors early on. 

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That is a nasty one. Bruno Martins Indi is late on Pedro as Chelsea counter, and he hammers the Spanish winger right on the top of the ankle. Could easily have injured Pedro, and the Dutch defender is booked.

Chelsea free-kick, and Diego Costa is back winding up defenders again. The referee steps in and WIllian hits the first defender. 

Bottom club Blackpool are winning 1-0 at home to Chesterfield after Mark Cullen scores in the second minute.

Hoping to make it four wins on the bounce, Colchester's Callum Harriott gives them the lead against Bradford.

Elsewhere, Rochdale have made it 3-0 against Shrewsbury and Fleetwood have taken a 1-0 lead away at Gillingham.

Arsenal are, as expected, posing more of the attacking threat. The graphic below shows the average position of the two sides and how Arsenal's centre backs may be a little bit quiet this evening.

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Diego Costa looks back to his menacing best tonight. He's working very hard indeed up front for Chelsea.