Matteo Guendouzi's personal trainer admits the Arsenal midfielder's style of play risks injury.

The France international is set to sign permanently with loan club Olympique Marseille this summer.

Serge Costa has been working with Guendouzi and says his all-action style is a risk to his long-term physical fitness.

Costa told L'Equipe: "In real life, Mattéo is tired but he compensates with mental freshness.

"We knock on wood so that he doesn't get hurt and he won't be able to last ten years like that."