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Spartak have a late corner, before a foul in the box is spotted by the referee and he then blows the final whistle to take the pressure off Barcelona who were given a big scare by the Russians tonight.
McGeady may have wasted Spartak's last chance to attack as he hesitates in a good position going forward and Xavi robs him of the ball...
Barcelona look like they have got away with it after a sloppy performance and that early injury to Piquet. We have three minutes of time added on...
Spartak are unable to get hold of the ball as Song, Busquets and Xavi play it around and then Messi charges forward, only for Villa to eventually concede possession as he handles it.
Emenike has the ball in the Barcelona half and then gives it away softly to frustrate his colleagues and manager, but he has had a good game in overall.
Barcelona are logically doing what they do best as they retain the ball and let Spartak do the running as the clock ticks down.
Spartak make their final change as Artem Dzyuba replaces Ari.
Pedro tries to wrap it up from the right, but his shot rolls wide of the left post.
Like Manchester City last night away at Barcelona's great rivals Real Madrid, Spartak will be so disappointed to go behind from 2-1 up. Sanchez crossed nicely from the left to set up Messi's important goal there.
GOAL! Messi is there again heading in from close range to save Barcelona's blushes. Unless there is another twist in the tail.
Emery brings on fellow Spaniard José Manuel Jurado for Källström.
Czech defender Marek Suchý fouls Sanchez just outside the penalty area and gets booked for it, then Xavi fires the free kick over the bar.
It's unsurprisingly all Barcelona pressure now and Villa should score as Dykan spills it but the Spaniard's shot is blocked.
The resulting free kick sees Xavi play it to Messi who fires at the wall.
Messi's free kick is blocked by Romulo using his hand and he receives a yellow card for that infringement.
Pedro is fouled by Insaurralde and Barcelona have a free kick 30 yards out. Meanwhile David Villa comes on for Tello.
Tello did brilliantly there as he reached the byline and played Messi in for a simple finish.
GOAL! Messi equalises from close range as Pedro's long cross from the right is picked up by Tello and he feeds the Argentine nicely from the left.
Spartak counter and win a corner which is taken by McGeady - the Barcelona defence deal with the threat this time though.
Tello finds space again on the left wing but his cross is high and inaccurate and falls to Dykan.
Barcelona are trying to crank up the pressure, Fabregas plays Tello in on the left but the young Spaniard is unable to cross or win a corner as he is marshalled well by the visiting defence.
Xavi's corner gives Song a decent chance to head on goal but he directs it over.
Messi wins and takes a free kick from about 30 yards out, but he hits the wall and it goes over for a corner.
Alexis Sanchez comes on and Alves' frustrating night ends early.
This is going to be an intense and interesting final half an hour or so, as Barcelona will not want to ruin their excellent home record in this competition.
More trouble for Barcelona as Emenike hits the deck in the box and wants penalty. The referee waves the players on and that would have been a harsh penalty.
What a surprise scoreline this is given the status and recent form of the two sides. Spartak Moscow deserve their lead though having fought tirelessly so far.
GOAL! A great counter attack from Spartak sees the Brazilian Romulo sprint forward to finish nicely past Valdes from the right.
Alves plays Messi in and the Argentine turns neatly but cannot beat the 'keeper.
Xavi is not quite finding his range from set pieces tonight and a free kick from him from 40 yards out is cleared easily.
Emenike is proving to be a real handful and it needs three defenders to close him down as he charges forward.
Then McGeady has a chance to shoot and fires it high over the bar from distance.
Xavi gives the ball away (yes Xavi!) and Spartak counter attack quickly only for Romulo to fire straight at Victor Valdes.
Now Alves wastes a chance to play Messi in from the right as his pass is too heavy and runs straight to Dykan.
Alves wants to make amends for his first half mishap but is caught offside. Just.
Emenike breaks again on the right but he has little to aim for and drifts a harmless cross over the Barcelona box.
A break in play gives us a chance for another statistic. This match is of course Vilanova's first in the Champions League as Barcelona coach and Guardiola's former No2 has a hard act to follow given that Barcelona reached at least the semi-finals in each of Guardiola's four seasons, winning the trophy twice.
Adriano slips in from the left and blast a low shot at goal, only for Dykan to gather the ball easily.
Evgeni Makeev comes on for Kirill Kombarov as the half gets underway.
The second half gets underway with the home team looking to brush aside this challange from their Russian guests.
The first half comes to an end and Spaniard Emery will be fairly pleased that his Spartak side are holding the Catalans thus far. Barcelona were marginally the better team in the opening 45 minutes though.
A shot from Xavi from the right hand side just outside the box goes wide of Dykan's goal on the goalkeeper's right.
Emenike is unhappy about something and has talked himself into a yellow card.
Fabregas is looking for a penalty as he goes down in the box, but has to settle for a corner. Xavi can't beat the first man as he takes it from the right though.
Kim Källström gets a yellow for a late challenge on Pedro.
Emenike and McGeady have been the best players so far for Emery's side as they have held their own in this intimidating arena.
Emenike looks to be injured and strolls over to the side of the pitch, but he's not coming off and takes some instructions from Emery.
Spartak clear the danger from the resulting corner taken again by Xavi.
Great save by Spartak 'keeper Andriy Dykan from a Cesc Fabregas header.
Kirill Kombarov fouls Alves on the right but again Barcelona waste the free kick.
Messi has a little trademark run across the opposition defence from the right, before giving the ball away too easily.
Now Song goes into the book as he smashes the breaking Emenike to the ground.
Kirill Kombarov brings down Pedro on the edge of the box, on the right side and goes into the book, but Barcelona cannot capitalise from a free kick in a good position.
Alves did not seem to be under pressure there but was not aware of the space behind him as he turned the ball towards his own goal from a Emmanuel Emenike cross.
GOAL! Very much against the run of play Dani Alves puts into his own net.
Spartak's only outlet at the moment is McGeady down the right, but when he breaks forward he tries a silly trick and is dispossessed easily.
Some typical Barcelona play in attack as Messi, Xavi and Pedro combine nicely. Whenever the home side lose the ball they work as hard as ever to get it back. Of course Pep Guardiola's work ethic is still stamped all over this team.
It's Spartak's turn to go on the attack as McGeady tires his luck but his shot is blocked.
Messi causing problems for the away team again, but as Xavi tries to play him through he's adjudged to be offside.
Messi finds space on the edge of the box and smacks a drive towards the Spartak goal. Just wide...
This will cheer up Barcelona fans after that early injury blow for Pique. Barcelona have won three of the last seven Champions League titles (2006, 2009, 2011).
Barcelona are well in control here and Song draws a foul from Ari.
That injury for Pique appears to be a twisted ankle and is a concern for Vilanova and his team. Eric Abidal is still far from fitness and Puyol is out for at least the next month.
Barcelona keep the pressure on to win another corner, taken by Xavi, but it results no danger for the visitors.
Another great start to a Champions League match for Barcelona with that early goal. A nice curling right foot strike from Tello as he cut in from the left.
GOAL! Spartak try to counter attack but they lose the ball and Barça themselves break forward, with youngster Tello repaying the faith of Vilanova to score a great goal and it's 1-0.
Xavi and Javier Mascherano are spraying some nice passes around but there is no penetration so far.
The night ends early for one of Barcelona's key men as Pique goes off and is replaced by Alex Song.
Pique hurt himself shooting at goal and is asking to go off the pitch to receive treatment.
Stat time: Barcelona have won the last two Champions League/European Cup finals played at Wembley, in 1992 and 2011. The final will be played there in 2013. A good omen for the home side?
Xavi takes the corner and although it's not a great delivery Gerard Pique gets on the end of it before smashing it well over the bar.
Messi's first moment of action and he slips into the box to force a corner.
An early corner for the men from Moscow comes to nothing despite an attempt at an overhead shot on goal from Juan Insaurralde.
Now it's Barcelona's time to play it around and get a feel for the ball, with the teams weighing each other up in the opening minutes.
A decent start from Spartak Moscow as McGeady makes early waves down the right, but there have been no clear chances on goal so far.
The game is underway in Barcelona, with the away team kicking-off and retaining possession in the opening seconds.
Tonight's referee, Milorad Mažić, is from Serbia, as are his assistants. According to UEFA, Mažić has swiftly risen to the top European level since becoming an international referee in 2009, having long been established as one of Serbia's finest officials. Let's see how he controls this tie.
Five minutes to go and the players are emerging from the tunnel. The traditional Barça anthem has just rung out around this huge stadium, just to remind the Spartak players of where they are!
Spartak appointed their Spanish coach Emery in the summer. He has never led a team to victory against Barcelona before. Indeed as coach of Almería and Valencia, Emery lost each of his six previous visits to the Camp Nou and is still seeking his first win against Barcelona at the 13th attempt. Emery's Valencia suffered two Camp Nou defeats in February, 2-0 in the Copa del Rey semi-final and 5-1 in the Liga. His overall record against Barcelona is W0 D5 L7. Source: UEFA.com
And why are Barcelona such clear favourites to win tonight? Well, in addition to having the majestic Messi in their hugely talented side they are unbeaten in their last 16 Champions League home games (13 wins, three draws).
Here are the match odds for tonight's game folks. Barcelona the clear favourites of course. Barcelona 1/12, Spartak 25/1, Draw 10/1.
The other teams in Group G are of course Celtic and Benfica, the Scottish team hosting the Portuguese side in Glasgow tonight.
Spartak started their league campaign in July but it has not been a great campaign so far for them and they sit seventh in the Russian league table with eight games played. The men from Moscow qualified for the Group Stage by overcoming Fenerbahce in the previous round. Barça need to keep their eyes peeled for the gifted Irishman Aiden McGeady tonight.
Ahead of this opening Champions League fixture of the season for Barcelona they maintained their perfect La Liga start at the weekend with a victory at Getafe, to make it four wins from four games. Striker David Villa continued his steady recovery from a leg break by netting the fourth goal in a 4-1 win on Saturday, but he is on the bench tonight. Vilanova instead puts young Spanish forward Cristian Tello into the starting line-up.
Spartak Moscow’s Spanish boss Unai Emery has seen his team take just one point from their last three league games before tonight’s match but says: "Crisis? I don't think so. We're working hard as a team but we are still a long way from a finished product. We're still trying to find the best way of organizing our attack."
Tito Vilanova (Barcelona): "The Champions League is the biggest competition alongside the league and we know that the first home game is crucial. This is a competition that motivates players especially. Spartak are a dynamic team who attack well on the break and will certainly cause us a lot of problems."
Demy de Zeeuw is absent for the visiting side as he serves a one-game ban. Spartak are also missing defender Nicolas Pareja, striker Welliton and captain Sergei Parshivlyuk due to injury.
Lionel Messi returns to the Barcelona starting XI after starting on the bench for last weekend's game against Getafe, when he came on to score twice in a good away win for the Catalans. As well as the recent loss of captain Carles Puyol to a knee injury for around six weeks, left-back Jordi Alba misses out with a virus that also kept him out at the weekend and Andres Iniesta is out with an adductor injury.
Teams: BARCELONA: Valdes, Alves, Pique, Mascherano, Adriano, Fabregas, Xavi, Busquets, Messi, Pedro, Tello … subs: Pinto, Bartra, Montoya, Thiago, Song, Villa, Alexis Sanchez. /// SPARTAK MOSCOW: Dykan, Insaurralde, K. Kombarov, Suchý, Rafael Carioca, McGeady, Källström, Kombarov, Romulo, Ari, Emenike… subs: Pesyakov, Bryzgalov, Makeev, Jurado, Bilyaletdinov, Dzyuba, Yakovlev.
Unusually for Barcelona in September there has been heavy rain for much of the day in the Catalan capital, but the sun was out before the match and the playing surface at the Camp Nou should be unaffected by the damp conditions earlier today.
Good evening and welcome to LIVE coverage of this Matchday 1 Group G Champions League tie between FC Barcelona and Spartak Moscow at the Camp Nou.