Rangers assistant manager Ally McCoist was "distraught" to learn of the death of his close friend Tommy Burns.
The pair had been Old Firm rivals for many years and worked together under Walter Smith in the Scotland set-up, until Smith and McCoist returned to Rangers in January last year.
Rangers were reeling from their UEFA Cup final defeat when McCoist was informed on Thursday morning that Celtic legend Burns had lost his battle with cancer at the age of 51.
McCoist told the Daily Record: "It had obviously been an emotional night on Wednesday and I got a call just before eight in the morning to tell me that Tommy had passed away.
"I was absolutely distraught. I don't mind saying that there was a tear in my eye.
"I loved Tommy. We all did. It's hard to think of anything else right now."
Manager Smith added: "If I have one regret about Tommy Burns, it's that I didn't know him for longer."
Celtic manager Gordon Strachan paid an emotional tribute to Burns on Thursday, saying the man who was his first-team coach and the club's head of youth was "top of the league" of football's gentlemen.
Rangers and Scotland captain Barry Ferguson described Burns as "a great man".
Ferguson told The Sun: "I woke up still gutted after the final and found out that Tommy was gone.
"It's so painful and such a waste of a life to lose such a great man at just 51."
Scottish FA chief executive Gordon Smith added his own tribute.
"Tommy Burns was a football man and a gentleman," Smith said.
"He was not just a Celtic legend, he was one of the most well liked and well respected men in Scottish football.
"He transcended the usual footballing rivalries that we have here in Scotland, with supporters from all clubs and from all walks of life full of admiration for the teams he built and the careers he helped shape.
"Scotland has lost a giant and so many people have lost a friend. My thoughts are with Rosemary and the rest of Tommy's family at this terrible time."
