The bond between members of one of the most influential football teams in history is unbreakable, but for 90 minutes on Saturday Pep Guardiola and Ronald Koeman must bury their friendship.

For Koeman, there is recognition that the footballing apprentice has become the coaching master. The Everton manager was trusted to mentor Guardiola, his former room-mate during the era of Barcelona’s legendary ‘Dream Team’.

Now he seeks to unlock the secrets of the coach he says may be the best in the world.