It's just not Barcelona's night. Another fine save from Proto as he dives down to his right to parry Messi's well-struck effort from 20 yards. Barcelona have knocked on the door all night, but they just haven't been able to solve this defence and goalkeeping duo!
90'
There will be three minutes added on at the end of this match.
88'
Diogo Figueiras gets yellow.
Diogo Figueiras is booked as he concedes a free-kick in a dangerous area. Luis Suarez takes the subsequent set-piece, but his strike is too central as Proto is able to beat it away confidently.
86'
STAT: Olympiacos have conceded 15 goals over their last five Champions League games; an average of three per match.
84'
U. Đurđević enters the game and replaces K. Fortounis.
The final change of the night is made here by the hosts, with Uros Durdevic replacing Fortounis up top.
82'
Juventus have equalised in Portugal, so a defeat would in fact eliminate Olympiacos tonight, while victory would ensure Barcelona's progression. A draw here does neither, though, but it does leave the hosts in a near-impossible predicament over the final two matchdays. They have to go for it here.
80'
SO CLOSE! Busquets produces a stunning ball over the top to play Suarez through, and the striker chips Proto with his first touch, but his effort lands on the top of the crossbar and bounces behind for a goal-kick! Final 10 minutes now in Greece and there's still nothing to separate the two sides.
79'
F. Pardo enters the game and replaces M. Carcela-González.
The hosts make their second change as they gear up for the final 10 minutes, with Felipe Pardo replacing Carcela.
77'
André Gomes gets yellow.
Instant impact from Gomes, but not the one he would have wanted, as he sends Diogo Figueiras crashing down near the touchline, earning his name in the referee's book as he's issued a quick yellow card.
Minute
Description
75'
G. Gillet enters the game and replaces V. Odjidja-Ofoe.
André Gomes enters the game and replaces Denis Suárez.
Olympiacos' first change of the night sees Guillaume Gillet replace Odjidja.
It's a third and final change here from Barcelona, as well, who introduce Andre Gomes at the expense of Denis Suarez.
72'
Barcelona have upped the urgency as they look for a way to break down this stubborn Olympiacos defence. Whatever happens over these final 20 minutes, the hosts deserve a ton of credit for how well they have performed up against one of the most formidable attacks in the world.
70'
It's worth noting that in the other Group D match, Sporting lead Juventus 1-0 in Portugal with 20 minutes to play. Should that result hold, Olympiacos would not be eliminated with a draw or loss - though it would take a miracle for them to advance. It also means Barcelona cannot secure their place in the knockout stage tonight, regardless of the result here.
68'
Approaching the final 20 minutes and it's delicately poised here in Piraeus. It is very much in the balance, and while Barcelona are enjoying the lion's share of possession, chances have been close to equally shared. It could go either way.
66'
STAT: Six of the last nine goals registered by Barcelona on the road in the Champions League have been converted by Messi.
64'
A quick injury update here, as Barcelona are reporting that Sergi Roberto has suffered a right hamstring strain and will be evaluated further tomorrow.
62'
I. Rakitić enters the game and replaces Paulinho.
Barcelona make their second change here, injecting a bit more creativity into midfield as Ivan Rakitic comes on to replace Paulinho.
INCHES WIDE! Oh my what a chance that was! Luis Suarez darts forward in attack, cuts inside onto his left in the penalty area and squares for Messi, but the skipper sends his off-balance shot wide of the far post with Proto caught out of position!
60'
Olympiacos respond with a nifty attack of their own, winning a free-kick in an advanced position on the left. A dangerous delivery is whipped in towards the far post, and Ter Stegen just manages to get a hand to it, sending it behind for a corner. Pressure building here.
58'
B. Engels gets yellow.
Engels arrives late with a challenge on Luis Suarez, sending him hard to the ground, and that will earn him a yellow card - the second Olympiacos player to be booked on the night.
56'
Deulofeu does well to run inside his marker and whip an inviting delivery across the face of goal, but it's turned aside smartly at the near post and behind for a corner, which is again dealt with perfectly by the hosts.
54'
Resolute defending here from the Olympiacos defence, despite coming under consistent pressure. They are looking comfortable and composed at the back, dealing with everything coming their way. Barcelona need more of a presence in the area.
52'
STAT: Barcelona have won 16 of their last 19 Champions League group games (D2 L1). They have also scored in 46 of their last 47 group games in the competition, the only exception coming against Benfica in December 2012 (0-0) when Barca were already guaranteed of topping their group.
50'
Possession dominated here by the visitors to start the second half, but no end product to speak of yet. Jordi Alba makes strides down the left and gets into a good position to whip in a cross, but sends it high, wide and not so handsome as it drifts behind for a goal-kick.
48'
Umtiti is crashes down after taking an elbow to the throat from Odjidja and play is brought to a halt as he needs a moment to collect himself on the turf. No yellow is issued but that's a warning for the Olympiacos midfielder and he won't get another.
46'
Here we go again!
45' +2
HALF-TIME: OLYMPIACOS 0-0 BARCELONA.
45' +1
Deulofeu enters the game and replaces Sergi Roberto.
An injury has forced Sergi Roberto off right at the end of this first half, replaced by Gerard Deulofeu.
44'
Olympiacos are in the ascendency as we approach half-time here, pushing the pace as they look to shock Barcelona with the opening goal right before the break. They're being urged forward by this raccous home support.
42'
Sergi Roberto gets yellow.
First yellow card of the night issued to a Barcelona player, meaning it's one for each side now, this to Sergi Roberto for a hard foul that has left his opponent in need of treatment.
39'
STAT: Olympiakos come into this encounter having only ever lost once in 10 previous home matches versus Spanish opposition in the Champions League (W4 D5).
37'
Excellent interplay! Great stuff from the hosts to break forward and carve out a chance, but the end product needs to be better! Some terrific passing leads to a shooting chance for Fortounis, but he can only poke the ball straight at Ter Stegen on the end of a lovely throughball!
36'
P. Tachtsidis gets yellow.
A skirmish ensues following a foul near the halfway line, and Tachtsidis is booked for his role in the altercation. Cooler heads prevail in the end.
35'
A chance to break for the hosts following a Barcelona corner, stemming from another Proto save, this time from a Messi free-kick, but Barcelona do well to snuff out the chance. Frustration setting in here for the hosts.
33'
Luis Suarez and Messi are doing an excellent job of coming to the ball, and moving well off it, which really has the Olympiacos defence at sixes and sevens - and it's taking the pressure off the Barcelona midfielders to be that link to attack, allowing them instead to park themselves and dictate the play.
31'
Well it certainly has been a dominating display from Barcelona as far as possession is concerned, but the hosts have had their chances as well. Another shooting opportunity here falls for Fortounis, but he can't hit the target from 15 yards, lifting over the bar. They can't afford to keep squandering these opportunities.
29'
STAT: Silvio Proto made nine saves in the last outing against Barcelona; no goalkeeper has managed more in a Champions League game this season.
27'
Dazzling footwork from Messi! Brilliance from the Barcelona talisman who dribbles his way through the Olympiacos defence and bursts into the area, but he's denied by Proto from point-blank range! The Belgian keeper has been excellent tonight for the hosts - but how long can he keep Barca out on his own?
25'
Ter Stegen and Umtiti provide a Halloween fright at the back for Barcelona, as their miscommunication leads to a chance which results in a corner for the hosts, but it comes to nothing in the end.
23'
Barcelona are ramping up the pressure here and they have come close again through Luis Suarez. They do have a couple of injuries to concern themselves with, however, as both Messi and Mascherano have picked up knocks.
21'
GOOD REACTIONS FROM PROTO! Messi gets a shot off from 15 yards that isn't particularly difficult, but it's the presence of Luis Suarez who tried to get a decisive touch on the ball from in close that forced Proto to be sharp - and he was, parrying at the near post!
19'
Barcelona seem to have broken the deadlock as Denis Suarez beats Proto at his near post, but the offside flag denies them the goal! A warning for Olympiacos, but nothing more as they escape unscathed.
17'
STAT: Only one of Olympiacos’ last 38 Champions League games has ended in a draw (W17 L20), it was against Benfica in October 2013 (1-1).
15'
Penalty shouts for the hosts as Elabdellaoui gets only a tame shot off from inside the area as a result of contact from Umtiti, but the referee waves claims away! It was a simple save in the end, but that's because of the contact - a questionable non-call!
13'
Another Barcelona attack comes to an end as Busquets tries to pick out Alba's break down the left wing, but the aerial pass is a touch too heavy and evades the full-back.The visitors remain in full control.
11'
Barcelona win two corners in quick succession and Messi takes both of them, but Olympiacos are able to survive, with goalkeeper Proto comfortably claiming the second to end the immediate danger.
10'
Engels puts an end to a weaving run from Semedo on the right with a perfectly timed sliding tackle inside the area. Get that wrong, however, and it was going to be a penalty to Barcelona.
9'
Barcelona are in possession and continuing to dictate the early proceedings, probing inside the Olympiacos half.
7'
STAT: Barcelona have avoided defeat in four of their last five visits to Greek clubs in European competition (W3 D1); letting in only one goal during that time.
5'
Barcelona very much in control to start this match, poking and proding in the attacking half, though they have yet to carve out a clear opening. The visitors are struggling to keep the ball when they win it back, largely having to camp out in their own end.
3'
This is a homecoming for Barcelona boss Ernesto Valverde, who spent three seasons in charge of Olympiacos over two seasons, winning three league titles and two domestic cups. They love him here and they have shown their appreciation for him already.
1'
AND THEY'RE OFF!
Hello and welcome to live coverage from the Karaiskakis Stadium in Piraeus as Olympiacos aim to keep their slim Champions League hopes alive when they host Barcelona!
This could prove to be a decisive night for both sides in Greece. Barcelona could book their place in the knockout stage with a win and a Sporting draw or loss, or a draw and a Sporting loss.
Ernesto Valverde’s side cannot clinch top spot in Group D, but they can just about do so with a win and a Juventus loss in Portugal – it would leave them needing just one point from their final two group matches to secure first.
Olympiacos’ chances of reaching the next round are hanging by a threat, and they can be officially squashed today should they fail to win, coupled with a Juventus draw or victory.
The Greek outfit have already made the daunting trip to Camp Nou and the Juventus Stadium, but their home form has not been particularly great either, losing arguably their most winnable Group D fixture, 3-2 at home to Sporting on matchday one.
CONFIRMED TEAM NEWS:
BARCELONA (4-4-2): Ter Stegen; Semedo, Mascherano, Umtiti, Alba; Roberto, Busquets, Paulinho, Denis Suarez; Messi, L. Suarez.
Ernesto Valverde is sure to receive a warm welcome tonight at his homecoming - more on that later - but first his team news. Javier Mascherano replaces the suspended Gerard Pique in defence, while Jordi Alba comes in at the expense of Lucas Digne. Nelson Semedo starts at right-back and Denis Suarez gets the call in attack, with Andres Iniesta and Gerard Deulofeu the ones replaced.
Scoreless at the break in Piraeus, but not for a lack of trying. Silvio Proto has been excellent for Olympiacos, producing a few fine saves to deny Lionel Messi and Luis Suarez, while the hosts have threatened as well at the other end. There certainly appears to be a goal or two in this match, and it's definitely anyone's guess right now as to who will be first to find the breakthrough.
Takis Lemonis makes four changes to his side from the reverse fixture at Camp Nou. Bjorn Engels, Diogo Figueiras, Panagiotis Tachtsidis and Kostas Fortounis replace Dimitris Nikolaou, Thanasis Androutsos, Sasa Zdjelar and Guillaume Gillet.
Ernesto Valverde's Barcelona are held against his former side as Olympiacos keep their slim hopes of advancing alive by preserving the goalless draw in Piraeus. Lionel Messi and Luis Suarez came close repeatedly, but could find no way to beat Silvio Proto and his woodwork.
That's all for our live coverage, thanks for following along. Goodbye!
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