Per Mertesacker has warned Arsenal must become more incisive in front of goal, saying: "We play and play and play until the opposing team scores."
Arsenal have seen their hopes of a successful season severely deteriorate in recent weeks, with a Champions League exit against Barcelona on Wednesday likely, their FA Cup campaign now over, and the club 11 points behind league leaders Leicester -- albeit with a game in hand -- after a run of one point from their last three games.
Former Germany defender Mertesacker said the 2-1 defeat to Watford in the FA Cup on Sunday was symptomatic of an approach in which the club's forwards are failing to seize opportunities in front of goal.
"What we do lack at the moment is we need to score at some point," Mertesacker told reporters. "It looks like we play and play and play until the opposing team scores. That is something we need to work on.
"We had the opportunities and the possibilities when they were 2-0 up to come back and we kept going. You have to give credit because we kept going and created chance after chance, 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.
"In the box we played and always found good positions, with the man in the right position, but we lacked that relaxation -- even to hit the target we did not do that sometimes. We missed it too often.
"The desire to play together and to be good at a team is there, you can feel that, even if there is a bit of negativity I can understand. I want as well that we go through here, I think we had the chances and we played in the right way apart from the fact we didn't score.
"That is something you need to do in football if you want to be successful. It looks like the longer the game goes, we rush and rush our decisions. It is still a learning process for us as a team."
Even so, the 2014 World Cup winner said Arsenal must fight to rescue their campaign, adding: "The season is not over. We play in a confident way [but] we maybe lack that bit at the end.
"What is really important in football, to be successful, we need to score."
Mertesacker also does not believe the Champions League should be written off despite a 2-0 home defeat to Barcelona in the first leg of the round-of-16 clash.
Speaking ahead of Wednesday's return match at the Camp Nou, he said: "We cannot afford to concede. We have to go there and try to attack, no matter what. That is the only possibility we have.
"We can be fortunate to have such a big game in front of us. I cannot predict. It is really hard. It is the ultimate team at the minute, so we are straight away under pressure and we have to go away from home."