Edinburgh-born Mackay passed away at the Queen’s Medical Centre in Nottingham.
Having joined Tottenham from Hearts in 1959, Mackay went on to achieve a historic league and FA Cup double with the north London club in 1961.
Spurs are set to hold a minute’s silence for their former captain, who also helped Derby to success as a player and coach before taking up a similar role with Swindon.
Ferguson, who fondly remembers Mackay as a contemporary and a friend, said: “I played against him once and I’m glad it was only once!
“He was hard. He was one of the hardest men of all time — a great Scottish player. You think of Dennis Law, Kenny Dalglish, Graeme Souness; Dave Mackay was along with them.
“He came back from two broken legs. He broke it against Manchester United actually, recovered and broke it again. He went on to play for Derby County and won the league and then became the manager, which was not an easy task because he followed Brian Clough, of course. But he’s had a fantastic career both has player and as manager. I always remember he was a good friend of mine.”
Spurs will hold their minute’s applause ahead of tonight’s game against Swansea at White Hart Lane, with black armbands being worn by the squad and a number of the club’s highest-profile former players paying tribute to Mackay at half-time.
Spurs boss Mauricio Pochettino is anticipating an emotional occasion for the evening kick-off, saying: “A very sad day and I want to send condolences to his family and friends. He is a legend, big player and manager, and it is a very sad day.”
The Scottish FA will also hold a minute’s applause in honour of Mackay before Scotland’s friendly against Northern Ireland this month.
Former Derby captain Roy McFarland spoke fondly about Mackay’s time at the Baseball Ground.
“The majority of pictures you see of Dave Mackay, he had his chest stuck out. That is how he played and that is how he lived his life.”