Ottmar Hitzfeld has admitted that Matthias Sammer is the most "annoying" player to have ever served under him.
The Switzerland boss worked with the legendary sweeper at Borussia Dortmund and reveals that he grew weary of the current Bayern Munich sporting director's overly critical attitude.
"The hardest [player to coach] was easily Matthias Sammer," Hitzfeld told Kicker. "Matthias had to complain after every victory, something I found a bit tiring and annoying.
"You cannot always list all the errors; otherwise you lose confidence."
Hitzfeld also revealed that he initially intended to become a teacher before going into coaching, confessing that it was some time before he felt as if he had chosen the right vocation.
"Being a coach is a gypsy life and involves much risk," the 64-year-old mused. "The first 10 years were marked by existential fears."
Hitzfeld and Sammer won the Champions League together at Dortmund, in 1997.