Arsenal boss Mikel Arteta concedes Gabriel Martinelli has been struggling for form.

Ahead of tonight's clash with West Ham, Arteta admits the attacker is performing better in the Champions League than the Premier League.

He said: "Difficult to put something onto it. Sometimes it's decision making. Sometimes, scoring, or missing a chance, or hitting the post, or receiving the ball, the difference is small details. He's really trying. He's a massive threat for us. Not only everything that he generates with the ball, but without the ball as well. The amount of time that he threatens the backline and the pressure he puts on the backline. It will happen again.

"I think confidence is not a problem for Gabi. Sometimes the efficiency and putting the break down and lifting your head up, for everybody it's the most difficult thing to do and finding that composure or timing in the box.

"Certainly a lack of confidence or trying is not going to be an issue for him."