Per Mertesacker believes in order to beat Barcelona at Camp Nuo the Gunners have to develop a killer instinct and beat the Catalans at their own game. The Gunners come into the fixture having lost the first leg 2-0 and face an uphill task of overturning that result and progressing into the next round for the first time in over six years.
The Gunners are going through a woeful phase at the moment, having won only one from their last seven games in all competitions which has all but ended their hopes of ending the season with a trophy. The Gunners are out of the FA Cup following a 2-1 defeat at the hands of Watford at the Emirates and are currently 11 points behind league leaders Leicester City, albeit having played a game less.
The game against Barcelona could not have come at a worse time for the Gunners, with Luis Enrique's men having won their last eight games in all competitions. They play the fixture after dismantling La Liga club Getafe 6-0 at Camp Nuo. Mertesacker, who was in the centre of defence against Watford, insists that Arsenal still have a chance against Barcelona, but for that they have to play out of their skin in both defence and attack.
"We cannot afford to concede against Barcelona. We have to go there and try to attack, no matter what, that is the only possibility we have," Mertesacker told Arsenal's official website.
"But at the moment we lack that killer instinct. We need to work on that if we want to be successful in the Premier League and the Champions League.
"We can be fortunate to have such big game in front of us. They are the ultimate team at the minute, so we are straight away under pressure and we have to go away from home. I think the confidence is there, we are just missing something.
"The season is not over. We play in a confident way, we maybe lack that bit at the end. The desire to play together and to be good as a team is there, you can feel that."