The first leg of this glamour tie provided something of a shock as Arsenal came from behind to record a 2-1 win at Emirates stadium against Barcelona but, after Lionel Messi's four-goal demolition job in the quarter-finals last season, the Gunners will be all too aware of the task that lies ahead of them at the Nou Camp. Messi arguably played a peak performance in the 4-1 win last season, with a flawless performance that contained four goals of the highest quality. It was a morale-sapping moment for Arsene Wenger's men as they were completely outplayed and outclassed by a side who lead the way in the pass-and-move game that Arsenal aspire to. However, almost 12 months later, it is a different side that arrives in Catalonia. A completely new backline has arrived at the Emirates, with Laurent Koscielny, Sebastien Squillaci and goalkeeper Wojciech Szczesny given the responsibilities of holding the fort alongside the rapidly improving Johan Djourou. While both Szczesny and Koscielny have been under the microscope of late for an error in the Carling Cup final against Birmingham, the general consensus over Arsenal's defence has been one of improvement - they have conceded 27 goals this season compared to 32 in the Premier League at the same stage last year. The emergence of Jack Wilshere has provided the side with a youthful burst of passion and exuberance, while striker Marouane Chamakh has brought a new dimension in the absence of the perennially injured Robin van Persie. With the Dutchman on the sidelines again, Chamakh and Nicklas Bendtner will be thrown into action at the Nou Camp, looking to press their claims for inclusion on a more regular basis. Barcelona, though, have remained much the same. Swapping Zlatan Ibrahimovic for David Villa up front, the technical excellence that pervades their every move has continued to find favour among the footballing purists and Villa seems to have settled immediately into their mesmeric rhythm without too much need for adjustment. With Messi continuing to score unprecedented numbers of goals and the addition of Javier Mascherano, Ibrahim Afellay and Adriano to bolster the squad depth available, Barcelona are even more of an incredible force and have still only dropped five points in La Liga this season. But without key centre-back duo Gerard Pique (suspended) and Carles Puyol (injured), the Gunners may smell blood. Arsenal player to watch: Jack Wilshere: Having received numerous plaudits for his mature performance in the first leg, the 19-year-old will be centre of attention again at the Nou Camp. With fitness doubts remaining over Cesc Fabregas, Wilshere's roll takes on added significance. Not only is he charged with harrying two of the best midfielders in the world - Andres Iniesta and Xavi - he also is asked to provide some thrust on the counter attack and use his vision and pace to push the opposition backwards. With his delicate touch and desire to move the ball quickly between his team-mates, Wilshere is capable of dictating the pace of the game and the Nou Camp will play host to his most important game to date. Barcelona player to watch: David Villa: Scorer of what could be a vital away goal in the first leg, Villa has blossomed in his first season at Barcelona and has bagged 17 goals in 25 games in La Liga. Not the biggest striker, his pace and movement are what makes him great as he hangs on the shoulder of the last defender and finds space to showcase his excellent finishing skills. Arsenal struggled to cope with his runs at the Emirates and he will again be asked to lead line, press the centre-backs and make space for the likes of Messi and Pedro to attack. Key Battle: Lionel Messi v Bacary Sagna: The greatest player in the world should need no introduction and it is obvious to all how important Messi is to his Barcelona side. With 27 goals in 23 games in La Liga, the Argentine No. 10 is in great form and, with the ball at his feet, there is simply no-one better. He netted four goals in a stunning performance at the Nou Camp against Arsenal last year, however, his inability to score in England haunted him in the first leg (even though he was unlucky to be flagged offside when heading home) this season and Barcelona can be stopped if their main man does not fire. Sagna will take a lot of the responsibility for tracking Messi as he drifts onto the right side of Arsenal's defence and, having missed the first leg due to suspension, will have a point to prove. Alongside his other defensive partners, Sagna's ability to hold a high line and play the offside trap will be of paramount importance and could be the key to stopping Barca's attacking threat. Trivia: The Gunners' best Champions League run came in 2006, when they reached the final - only to lose 2-1 to Barcelona. Stats: Thirty-six of Barca's 37 league goals at the Camp Nou this season have come from open play. Set pieces and penalties are not their thing. Prediction: It would be the result of the season if Arsenal could upset Barcelona on their own turf, although a draw would be enough to see them through to the next round. One feels that Messi, however, has different plans and could have a similar impact to last season. Credit:Espn.com Catch the exclusive coverage of Barcelona vs Arsenal live on Joy Sports and Adom TV on Tuesday March 8, 2011 from 7:15 pm. Kick off is at 7:45 pm. join the match discussion on our website http://www.multitvworld.com/match