Former Chelsea and Germany midfielder Michael Ballack says Kai Havertz needs to toughen up.

Havertz has struggled since moving from Chelsea to Arsenal over the summer.

Ballack said, “Kai Havertz has outstanding skills.

“But as already mentioned: he seems a bit too reserved for me. You need a certain robustness and mentality, especially abroad, to assert yourself in difficult situations. I hope he gets it done.

“In my opinion it is still too early for that (an exit). He should assert himself at Arsenal by all means possible."