Arsenal defender Per Mertesacker has been impressed by the progress of Serge Gnabry.

The teenager made his Premier League debut against Norwich on Saturday and became the youngest German to appear in the Champions League after coming off the bench against Schalke at 17 years, three months and 11 days.

"Arsenal are always searching for this type of player who have shown their qualities very early," Mertesacker told

"They get them very early, so let's try to put confidence to him. He is learning a lot in training and these games are very important for him."