Arsenal boss Arsene Wenger is convinced former Sunderland boss Roy Keane won't be lost to football.
"It is a surprise [that he has resigned], but I can understand that," the Frenchman told arsenal.com.
"He is a passionate man, and I regret he leaves the job. When you are passionate, especially at the start of this career, you suffer immensely physically. Also, because he is a passionate man, there is no other way for him to be in the job.
"When you are passionate about the game, you go out of it and then come back into it because there is no other way to be happy. That is why I believe he will be back."