Manchester City manager Pep Guardiola has credited Ronald Koeman for shaping his managerial philosophy.
The Spaniard is preparing his side for the visit of Everton on Saturday, where he will be reunited with his former Barcelona team-mate.
Koeman shared a room with the former Bayern Munich boss while the pair were at the European heavyweights in the 1990s.
Guardiola said he owes a debt of gratitude to the Dutchman - and revealed Koeman changed the way defenders were viewed in world football.