Arsenal manager Mikel Arteta has admitted he is concerned about Gabriel Martinelli after Monday's loss to Everton.

The Brazilian had to be withdrawn in the second-half as Everton came from behind to win 2-1.

And Arteta confirmed a hamstring injury was the cause of Martinelli's substitution.

Asked about the severity of the injury, Arteta told reporters: "I don't know we will have to assess him.

"He felt something in his hamstring so I'm not very positive about it."