Former Real Madrid Castilla coach Alberto Toril said he had learned from working with Jose Mourinho that "either you were his friend or you were his enemy."
Toril was in charge of Madrid's youth side from 2011 to 2013, when Mourinho was first team coach.
Tensions between the pair were widely reported at the time, with Mourinho publicly criticising Toril's development of young talent.
The long-serving youth coach was first banned from attending Mourinho's training sessions and then sacked mid-season by club president Florentino Perez.
Toril, now coach of Segunda side Elche, told Onda Cero: "He [Mourinho] was very extremist -- either you were his friend or you were his enemy.