Chelsea's fifth defeat of season
FT: Arsenal 2-3 Olympiakos
Arsenal P2 L2 - Bayern Munich next
Lewandowski hat-trick for Bayern
Five defeats in 6 games for English teams so far
Belarusian champions BATE Borisov have stormed into a 3-0 lead at home to Roma in the most surprising scoreline of the night so far.
But not to be outdone, Bayern Munich scored four in the first half hour (two for Robert Lewandowski) to lead 4-0 against Dinamo Zagreb.
And in the other game in Chelsea's group, Dynamo Kiev are 1-0 up at Maccabi Tel Aviv.
Arsenal 1-2 Olympiakos
Arsenal have got to play Bayern Munich twice in this group yet!
Arsenal 1-2 Olympiakos
Arsenal having almost all of the ball but it's what you do with it that counts...
Image source, .Text us on 81111
Michelle, Middlesbrough: Hey! I am mortally offended by the Nissan Sunny remark (see 20:24). I had one called Nessie (who had a George cross bonnet for the 2004 Euros) and he could do a three-point turn with the best of 'em!
Arsenal 1-2 Olympiakos
Phil McNulty
BBC Sport chief football writer
"Murmurs of discontent around The Emirates as Arsenal troop off. Arsenal simply must get back into this game - and why on earth, with the stakes so high, has manager Arsene Wenger left first-choice keeper Petr Cech on the bench in favour of David Ospina?
"If he is carrying any sort of injury, why is he on the bench? Does not make any sense and Wenger must hope it is not a costly decision."
#bbcfootball
Stephen Noakes: That fourth Premier League Champions League place is looking at real risk all of a sudden...
Porto 1-1 Chelsea
Mark Lawrenson
BBC Radio 5 live in the Estadio do Dragao
"The goal is only what Chelsea have deserved.
"But Iker Casillas was stood behind the wall, almost in the middle of the goal. Anything that bends in around him was always going to be a goal.
"That will change Jose Mourinho's half-time team talk, but I think they did really well under all sorts of pressure in that opening 45 minutes."
Arsenal 1-2 Olympiakos
Arsenal 1-2 Olympiakos
Willian (45 mins)
Image source, ReutersWith the last kick of the half! Referee Antonio Lahoz blows his whistle seconds after the ball hits the net and Chelsea are level.
His team-mates may be struggling, but Willian is on fire. Wonderful free-kick. Over the wall, into the net. Chelsea had three men on the end of the wall, worked it well.
Image source, ReutersPorto 1-0 Chelsea
Mark Lawrenson
BBC Radio 5 live in the Estadio do Dragao
"Chelsea have been the better team, it's just defensively they've been caught out. Again.
"Their build-up play has been excellent, and they will get opportunities here. Every time they get into the Porto box, there's panic."
Porto 1-0 Chelsea
A great run from Yacine Brahimi and Andre Andre was on hand to tap home for Porto.
Not shown: Branislav Ivanovic defending like me on the 5-a-side court on a Tuesday lunchtime...
Image source, .Porto 1-0 Chelsea
Porto have been very bright, they have plenty of rapid attacking threats. But one or two of this Chelsea team look done in. What's happened to Branislav Ivanovic?
Championship update
Fulham are down to 10 men after Tom Cairney was shown a straight red for a two-footed challenge on Wolves' Adam Le Fondre.
Arsenal 1-2 Olympiakos
Mark Lawrenson
BBC Radio 5 live in the Estadio do Dragao
"In the Champions League, you pick your best team. You certainly pick your best goalkeeper."
Porto 1-0 Chelsea
Mark Lawrenson
BBC Radio 5 live in the Estadio do Dragao
"That's a brilliant goal from Porto. Brahimi got himself running at Ivanovic, who knew he couldn't tackle him.
"Begovic did really well to stop the shot but it came straight out to Andre. The goalscorer reacted quickest, but Begovic nearly got to the second one as well.
"It's against the run of play."
David Opsina OG (40 mins)
Image source, Reuters"What do those officials behind the goal do? What's the point of them?"
We've all asked it a million times, and now they make a big call. First of all, it's awful from goalkeeper David Ospina as he collects a corner from the right and then somehow lets it though his hands to bounce on - or just over - the line.
He gathers it in but the official behind the goal says goal!
Andre Andre (39 mins)
Image source, ReutersAsmir Begovic makes a superb save but he can't deny Porto.
Again, Chelsea skipper Branislav Ivanovic is at fault in the build-up though. Yacine Brahimi takes him on, Ivanovic has the mobility of a 1984 NIssan Sunny, Brahimi's shot is palmed out by Begovic and Andre Andre follows it up with a powerful strike.
Image source, ReutersArsenal 1-1 Olympiakos
A six-pass move by Arsenal was well-finished by Theo Walcott...
Image source, .Arsenal 1-1 Olympiakos
Dr Spits: Nice heel flick, Ox.
Ben Hoare: Those people who say Theo Walcott isn't a striker need to remember he now has 16 goals in his last 19 starts.
Kerry Peter Parvin: He's really growing into being a striker! Girwho?
Get in touch at #bbcfootball,, external pop on to the Match of the Day Facebook page, external or BBC Sport's Google+ area.
You can also text us on 81111 in the UK only - don't forget to say who you are and where you are.