Arsenal captain and defender Per Mertesacker has blamed their recent string of losses on the lack of a killer instinct.
The gunners were dumped out of the FA cup by Watford, with Welbeck missing an open goal in the 2-1 loss.
The exit comes after Arsenal recorded losses to Swansea, United and Barcelona.
“What we do lack at the moment is we need to score at some point. It looks like we play, and play and play until the opposing team scores,” Mertesacker told reporters.
“That is something we need to work on. We had the opportunities and the possibilities when they [Watford] 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.
“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.”