Uefa Champions League 2015-16: Arsenal 2-3 Olympiakos - Porto 2-1 Chelsea - as it happened

So another bad night for Premier League clubs in the Champions League and once again the coefficient, which dictates the amount of places on offer to clubs in Europe's premier club competition, will take another battering.

That is all we have time for from The Emirates Stadium. We wait to hear from Arsene Wenger in the next 30 minutes or so regarding his selection tonight. We're back with live coverage of Manchester United and Manchester City's games against Bundesliga opposition in Wolfsburg and Borussia Monchengladbach, but until then goodbye.

Oxlade-Chamberlain shoots wide and that is it, Olympiakos claim their first ever win on English shores. Arsenal have zero points from their opening two group games, ahead of facing Bayern Munich in back-to-back matches. Another harrowing night for Premier League clubs in the Champions League.

Full time in Portugal and Jose Mourinho's Chelsea are beaten at his former club Porto. Diego Costa somehow didn't equalise late on. Can Arsenal grab a point?

Chelsea are meanwhile pushing hard for an equaliser themselves as Porto retreat into their shell but as yet Jose Mourinho's side are being frustrated.

Four added minutes to be played at the Emirates Stadium. Arsenal need them all.

Sanchez's free-kick from the right is turned over by Roberto. Has felt like a one-man effort from the Chilean this evening at times. Just a minute plus stoppage time to go.

Last throw of the dice from Arsene Wenger. Joel Campbell on for Arsenal. Less than five minutes remaining.

Goal: Bate Borisov 3-2 Roma (Torosidis)

Goal: Barcelona 2-1 Bayer Leverkusen (Luis Suarez)

Goal: Barcelona 1-1 Bayer Leverkusen (Sergi Roberto)

Porto within inches of going 3-1 up as Danilo heads against the post. Chelsea living dangerously as the game enters the final 10 minutes. Arsenal meanwhile continue to be frustrated.

Mesut Ozil's free-kick from the right-hand channel of the penalty area and Roberto makes a fine two-handed save. Bit of handbags now between Ozil and Pardo on the touchline ends with the German being yellow-carded for an illegal hand-off.

Chance out of nothing for Chelsea as Willian's corner is headed goalwards by Ivanovic but is flies wide of post and bar. Big chance, in the context of the pressure being exerted by Porto, who have been much the better side in this second half.

More pressure from Porto, who try to put the game out of sight, but Chelsea hold firm. Ramies and Pedro have both made way but the visitors are playing the role of survivor.

Goal: Bate Borisov 3-1 Roma (Gervinho)

Goal: Arsenal 2-3 Olympiakos (Alfred Finnbogason)

Incredible passage of play at The Emirates. Arsenal equalise through Alexis Sanchez's smart header but they are level for just a minute as Olympiakos march down the other end and go back in front for a third time. Cambiasso plays the ball over the Arsenal back four and when the cross comes in, half time substitute Finnbogason converts from five yards. Amazing.

Goal: Arsenal 2-2 Olympiakos (Alexis Sanchez)

Change for Chelsea as Eden Hazard replaces John Obi Mikel. No need to explain the thinking there. Mourinho searching a much-needed equaliser.

Change for Chelsea as Eden Hazard replaces John Obi Mikel. No need to explain the thinking there. Mourinho searching a much-needed equaliser.

Roberto turns over a deflected Oxlade-Chamberlain cross for a corner, from which the 'keeper beats away Cazorla's effort. A second wind from Arsenal.

Second change for Arsenal as Aaron Ramsey replaces Francis Coquelin. The equaliser almost comes immediately. Three times Roberto is tested from Sanchez's cross, first from his own defender before he denies Mertesacker and then Cazorla's shot is cleared off the line by Cambiasso. One of those moments that makes you think it could be Olympiakos' night.

Chelsea under real pressure in Portugal and they twice almost go behind. With very little in reserve on the bench in an attack sense, those on the pitch have to get it done for the Blues. Diego Costa incidentally, has been superb for the league champions.

Change for Arsenal enforced through injury as Laurent Koscielny is replaced by Per Mertesacker.

Goal: Bayern Munich 5-0 Dinamo Zagreb (Robert Lewandowski)

Goal: Maccabi Tel Aviv 0-2 Dynamo Kiev (Junior Moraes)

Goal: Porto 2-1 Chelsea (Maicon)

Games across Europe back underway it must be said. Two more games going by without an English winner, too.

Players out at The Emirates, where a goal-line technology debate is brewing after David Ospina dropped the ball from a corner, dangerously close to his own line but I am yet to see an angle which conclusively shows the ball crossed the line. The Michel Platini-run Uefa says goal-line technology is too expensive. I'll let you create your own punch-line.

Half time across Europe and it has been quite a first half. Arsenal are facing a second straight defeat in as many Champions League group games after David Ospina's mistake gifted Olympiakos a lead for the second time. It is better news for Chelsea however, as right on the stroke of half-time Willian has curled the Blues level after Andre Andre's opener. An intriguing 45 minutes in prospect for both teams.

Goal: Porto 1-1 Chelsea (Willian)

Goal: Olympique Lyon 0-1 Valencia (Feghouli)

Goal: Porto 1-0 Chelsea (Andre Andre)

Goal: Arsenal 1-2 Olympiakos (David Ospina own goal)

An absolute clanger from David Ospina puts Olympiakos back in front. An in-swinging corner from the left comes in towards the Chilean, but he drops the ball into his own net, a goal given by the officials despite inconclusive video evidence.

Goal: Bate Borisov 3-0 Roma (Mladenović)

Goal: Zenit 1-0 Gent (Dzuba)

Goal: Arsenal 1-1 Olympiakos (Theo Walcott)

The Gunners bite back straight away, as Sanchez plays a slide through ball to Walcott who is allowed onto his right foot by Siovas and he slots past Roberto.

Goal: Arsenal 0-1 Olympiakos (Felipe Pardo)

Disaster for Arsenal as the Greek champions take the lead. Fortounis' shot is deflected over and from the resulting corner the ball comes back to Pardo who takes aim and his shot hits Alex Oxlade-Chamberlain and flies past the outstretched Ospina.

Half a chance for the hosts Porto. Maxi Pereira escapes down the right and his cross deflects of Ivanovic and agonisingly roles across the six yards box. Chelsea solid so far it must be said.

Goal: Bayern Munich 4-0 Dinamo Zagreb (Robert Lewandowski)

Goal: Bayern Munich 3-0 Dinamo Zagreb (Mario Gotze)

Chance for Olympiakos at the Emirates. Some nice build-up play ends with Kostas Fortounis breaking into some space but he thrashes his shot wastefully wide. A better chance than the resulting shot suggested.

Goal: Barcelona 0-1 Bayer Leverkusen (Papadopoulos)

Goal: Bayern Munich 2-0 Dinamo Zagreb (Robert Lewandowski)

Noticeable that despite Chelsea having the better of the chances at Porto, they are committing very few players to set-pieces, with just four going forward for their latest corner. Porto have offered little it must be said and Mourinho will be content thus far.

The battle between former Real Madrid and Barcelona players continued in Portugal as Casillas denies Pedro, after he was put through by Willian. Chelsea outnumbered Porto there but the Spanish goalkeeper comes to their rescue.

Goal: Bayern Munich 1-0 Dinamo Zagreb (Douglas Costa)

Goal: Bate Borisov 2-0 Roma (Mladenović)

The pressure continues to come from the Gunners and Theo Walcott is the latest player to get free but Roberto makes a relatively easy save to deny the England forward. Arsenal well on top.

Goal: Bate Borisov 1-0 Roma (Stasevich)

From the the resulting corner, Arsenal create the best chance of the half as five players break against three Olympiakos defenders. Sanchez feeds Oxlade-Chamberlain but he can only find the side-netting.

Brief moment of excitement for Arsenal as Alexis Sanchez goes past two defenders but when he overruns the ball he goes down and wants a free-kick. At the other end, Kasami's miss-hit shot hits Ibeye and it takes a last ditch clearance from Koscielny to clear the danger.

Chance for Chelsea in Portugal. Diego Costa toys with the Porto defence and after twisting an turning he plays in fellow-countryman Cesc Fabregas but Casillas keeps out the effort from the former Barcelona man.

Bit of a tense start from Arsenal, having plenty of the ball in deep areas but yet to string together more than a handful of passes in the final third. Alex Oxlade-Chamberlain and Hector Bellerin looking particularly dangerous.

Goal: Maccabi Tel Aviv 0-1 Dynamo Kiev (Yarmolenko)

First news of the night from Portugal comes in the form of Jose Mourinho, who delays taking his seat until after the game has kicked off thus avoiding the glare of the dozens of photographers.

Underway across Europe. All the goals as they go in tonight. Don't go anywhere.

Teams are out at The Emirates Stadium and the music is blaring. Almost ready to go on matchday two in the Champions League.

Iker Casillas makes his 152nd Champions League appearance tonight, and is now the record appearance maker in the competition on his own, ahead of Xavi. How he would love to mark it by putting one over Mourinho.

So how will tonight work in terms of coverage? Well I will be across everything at the Emirates Stadium and that will be central to the live blog tonight. I will have updates from Porto vs Chelsea and all the other six games across Europe, with all the goals as they go in. No need to move, really.

It is firmly gloves and scarf weather at The Emirates Stadium tonight, where it is very chilly in the Arsenal press box. I will have to imagine what wearing them would have been like. Half time cannot come soon enough.

No such glaring questions regarding Arsenal's team at the Emirates Stadium tonight. Olivier Giroud naturally misses out through suspension but it is a major boost that Francis Coquelin, who has been absent for the last two games, starts at the base of the midfield - a position the Gunners have looked awfully exposed in particularly in Europe.

Plenty of curiosity regarding the Chelsea team that has been named to face FC Porto tonight, with three of Jose Mourinho's big hitter left on the bench. Mourinho confirmed that everyone bar Thibaut Courtois was fit for the game, and having said he wanted to make six substitutions at half time in the draw with Newcastle and then slammed his senior players yesterday, he pulls three of them from his starting XI. All is not well with the Premier League champions.

The Olympiakos team has dropped and you will notice the inclusion of three players formerly of the Premier League, with Esteban Cambiasso, Pajtim Kasami and Brown Ideye named in their starting line up.

A word about Chelsea's opponents FC Porto, who as expected name Iker Casillas in goal. You may remember he and Jose Mourinho had a certain falling out during their time at Real Madrid.

Team news:

Olympiakos: Roberto; Elabdellaoui, Botia, Siovas, Salino; Cambiasso, Kasami; Pardo, Fortounis, Seba; Brown Ideye

Quite a strange stat to present you with prior to kick-off; Arsenal have never lost on matchday two in the Champions League with 16 wins and four draws coming from their 20 matches. Olympiakos have an encouraging record from a Gunners point of view too, having lost all 12 of their visits to British shores. Points towards a home win?

We are yet to get the Olympiakos team news in yet despite being less than an hour from kick-off, but let's wrap up the sides named by both Arsenal and Chelsea.

There are two notable inclusions in the Arsenal side, with Francis Coquelin returning following a knee problem while Gabriel Paulista comes into the centre of the defence in place of Per Mertesacker.

Chelsea leave out Nemanja Matic, Eden Hazard and John Terry from their team, with Kurt Zouma, John Obi Mikel and Ramires coming in. Neither Loic Remy or Radamel Falcao on the bench.

Arsenal vs Olympiakos

Arsenal: Ospina, Bellerin, Gabriel, Koscielny, Gibbs; Coquelin, Cazorla; Oxlade-Chamberlain, Ozil, Sanchez; Walcott.

Teams:

FC Porto vs Chelsea

FC Porto: Casillas, Maxi, Maicon, Marcano, Martins Indi, Danilo, Rúben Neves, Imbula, Brahimi, Aboubakar, André.

Chelsea: Begovic; Ivanovic, Zouma, Cahill, Azpilicueta; Mikel, Fabregas; Ramires, Willian, Pedro; Diego Costa.

While we await confirmation of the teams, here is a run down of what we know about Arsenal and Chelsea's expected line-ups ahead of tonight's games.

Arsenal are without Mikel Arteta and Mathieu Flamini after both players picked up injuries in the win over Leicester. Danny Welbeck and Jack Wilshere are out until December while Olivier Giroud is also missing through suspension.

Chelsea meanwhile have no such concerns with Jose Mourinho having a full squad to chose from bar Thibaut Courtois who is still out with a knee injury. Both teams should be confirmed in the next few minutes.

After a harrowing first week upon the return of the Champions League a fortnight ago, the Premier League contingent look to put things right on matchday two in Europe's premier club competition. Chelsea were the only team to record a victory during the opening week, beating Israeli side Maccabi Tel Aviv, but 2004 winners FC Porto - a former side of Jose Mourinho - represent far tougher opposition. Arsenal meanwhile, victims of Dinamo Zagreb's first ever Champions League win, endured contrasting fortunes in the Croatian capital and are under pressure to belatedly kick-start their campaign against Olympiakos.

I am situated at The Emirates Stadium as Arsenal search for their first three points of the campaign but I will keep you abreast of all the goings on from across Europe where the likes of Barcelona and Bayern Munich are in action, while keeping you updated on goings on at the Estádio do Dragão where Chelsea face Porto.