The teenage striker scored with his first touches of the ball to open his account for the club, and earned rave reviews from his German team-mate.
"He's a very strong and intelligent player," Mustafi told Arsenal.com. "He's a good striker and he's hungry.
"I think at this age in strikers you can always see that hunger to score and they always want to do something in the box, and I think for him it was really nice. He came on in the last game as well and this time it was his first touch he scored with, so I'm very happy for him because I think this is something that is very important.
"We all started as young boys and everyone knows the feeling of how difficult it is to come to the first team and perform the way you perform with the youth team, so we have to give him credit and hope it's a sign of more coming in the future."