Celtic captain Scott Brown was controversially sent off as his side narrowly failed to hold out against Barcelona in Glasgow.
Brown was shown the red card by French referee Stephane Lannoy on the hour mark after a seemingly innocuous collision with Neymar, though it appeared that Brown flicked a boot at the Brazilian as he fell and trod on his hand.
The Hoops came close to opening the scoring moments later when substitute James Forrest, on for Mikael Lustig, had a powerful volley saved by Victor Valdes before Charlie Mulgrew came within inches with a header.
However, the Scottish champions were dealt another blow in the 76th minute when Cesc Fabregas headed Barcelona into the lead.
Celtic keeper Fraser Forster denied Neymar twice and also substitute Alexis Sanchez, who had set up the goal, in the closing stages as gaps opened up in the Parkhead defence. But it was a spirited performance by Neil Lennon's side, who as expected chased the ball for most of the game, especially in the first half.
Despite that, Forster had little to do and the home side were given a round of applause by their fans at the end of the game. Celtic play Ajax in their next group fixture on October 22 and after losing 2-0 to AC Milan in their Group H opener, they will have to fight for Champions League survival without the suspended Brown.
The 'Tifosi' display inside Celtic Park before the game, where coloured cards were held up by fans all around the packed stadium, set the mood for another night of European excitement in the east end of Glasgow.
Lennon kept changes to a minimum. Lustig replaced striker Teemu Pukki, who started on the bench where he was joined by Forrest who had recovered from a virus and midfielder Beram Kayal, back from a groin complaint. Barcelona were without Lionel Messi as well as Javier Mascherano, Jordi Alba and Carles Puyol but the Catalans still had a host of big names including Fabregas, Andres Iniesta, Xavi Hernandez and Brazilian star Neymar.
Barca had dominated possession almost from the start of the game when the two sides met last November and in the early stages of this encounter they pulled the home side all over the park. However, in the fifth minute Celtic cut their way through the visiting defence for the first time and Barca keeper Valdes denied Georgios Samaras at the expense of a corner which, although it came to nothing, boosted the home side's belief.
The Catalans, playing in an unfamiliar all-black kit and without an out-and-out centre forward, kept a tight grip on the match. Neymar had a drive from 25 yards in the 17th minute which went wide of the post before Iniesta dropped his shoulder to leave Hoops midfielder Charlie Mulgrew for dead before driving over the bar. It was an indication of Barca's impotence, despite their control of the ball.
Barca seemed in no rush to get a goal but five minutes from the break Neymar got a flick to a Dani Alves cross only to see the ball zip past the near post. In the final seconds of the first half Forster punched away a Xavi free-kick from wide on the left, after Lustig had fouled Neymar, but the resulting corner came to nothing.
The second period began with Tata Martino's side again monopolising possession without looking like scoring. Brown's dramatic sending-off, for foolishly aiming a boot at Neymar after fouling the Barca forward from behind, gave an edge to the atmosphere with the home fans clearly unhappy at the fleet-footed Brazilian.
As the home side dropped deeper, Forster made a save from Marc Bartra's long-range effort. Lennon replaced Anthony Stokes with Kayal and Lustig with Forrest in the 68th minute to bring some freshness into his tiring team.
Four minutes later Celtic, fuelled by a sense of injustice, almost took the lead when Forrest fired in from the edge of the the box with Valdes having to make a great save. From Kris Commons' corner Mulgrew headed past the post and for a moment the thought of another unlikely win over Barca permeated the Hoops supporters.
But moments after he had replaced Pedro Rodriguez, Alexis Sanchez raced down the right and crossed for Fabregas to head across Forster and in to the net.
With four minutes remaining Forster then made a great double save, first from Neymar's drive and then from Alexis Sanchez who had followed up, at the expense of a corner, which yet again for the visitors proved fruitless. In the dying seconds of normal time Forster had another great save from Neymar when he raced clear of the fatigued Hoops' rearguard.
With no points from two games, Celtic will need something from the forthcoming double-header with Ajax to keep their Champions League hopes alive.
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