An emotional Howard Wilkinson called Gary Speed "a star in the true sense" following the shock news of the former Leeds United player's death.
Wilkinson led Leeds to the old First Division title in 1992, the final season before the Premier League began, and Speed was an integral member of the side.
Wilkinson told BBC Radio Five Live: "The players I worked with represented all colours of the rainbow in terms of character but in Gary's case he was a star in the true sense. For him - at 42 - to leave us is such a tragic loss.
"He had a life of success to look forward to I'm sure.''
"It's unbelievable, I'm still struggling to get my head around it. I've known Gary since 1988 when I joined Leeds and I've rarely come across a better balanced, lovely, genuine person.
"He was a terrific player - not as gifted as some but he made the most of everything he had - worst of all for me I knew his parents, in particular his dad, his lovely wife and family - I just find it very very difficult to come to terms with it.
"I cannot start to try and understand what his family are going through at this time.
"We're not born footballers and like everyone else they had a talent and that became their job, but basically they are born people and subject to all the stress and strains and the good things that happen to one in life.''
A Leeds United spokesman said: "We are stunned to learn this news. The club expresses its deepest sadness. Gary was very well thought-of throughout the game. He was a very likeable and popular man. It's very difficult find words to describe how we're all feeling right now.''
Tony Dorigo, who played alongside Speed in the team which won the 1992 title, said on Twitter: "I'm completely shocked and saddened. A great guy and a better team-mate you couldn't wish for. Speedo, RIP mate.''
Everton chief executive Robert Elstone said in a statement on the club's website: "It is with the very deepest of regret that we have today learned of the passing of Gary.
"Gary was a popular player during his time here at Goodison Park and on behalf of the Board of Directors, management, players, staff and fans of Everton I would like to extend our sympathies to his family at this extremely difficult time.''
A statement from Sheffield United, where he finished his playing career and went on to manage, read: "Everybody at Sheffield United is extremely shocked and saddened to learn of the death of former player and manager Gary Speed. Thoughts are with Gary's family and friends at this distressing time.''
Bolton, for whom Speed made more than 100 appearances between 2004 and 2008, also paid tribute in a statement on the official club website.
"Bolton Wanderers is deeply saddened to hear of the death of former player and club captain Gary Speed and wish to extend our deepest sympathy to his family,'' the statement read.
Bolton chairman Phil Gartside added: "We are all stunned at the news of Gary. Not only was he a top-class professional but was a wonderful person who is very fondly remembered by all of us and our thoughts and heartfelt condolences are with his family at this time.''
Newcastle issued a statement which read: "The board, manager, staff and players of Newcastle United FC are today deeply saddened to learn of the tragic death of Gary Speed.
"Gary was an inspirational and much-loved player at Newcastle United during his time with the club from 1998 to 2004, making 285 appearances and scoring 40 goals.
"He was an excellent servant to the club, the ultimate professional, and an exceptional role model for younger players. Gary will be deeply missed by everyone at Newcastle United. Our condolences go out to his family at this very sad time.''
Alan Shearer, who played alongside Speed at Newcastle for six years between 1998 and 2004, formed a close friendship with the Welshman and said: "Gary was a magnificent person, bright, fun and a wonderful family man - he lit up every room he walked into. I am proud to have been his friend and will miss him dreadfully.''
Liverpool manager Kenny Dalglish, who signed Speed when he was manager of Newcastle, said his side's match with Manchester City had been put in the shade by the news of the Welshman's death.
"He was a smashing lad and was really well respected,'' said Dalglish. "We don't know the circumstances obviously, and there'll be a lot of people who are saddened at what's happened, but I think the most important people at this particular moment in time is his wife and kids - they must be absolutely devastated.
"It's a times like this that the football becomes a wee bit irrelevant. He was a very respected man in and around football, not only for his ability but for the guy as a person. I signed Gary for £5 million from Everton and he did a fantastic job for us at Newcastle, during the time I was there and after I'd left as well.''
Newcastle defender Steven Taylor, who came into the first team at St James' Park when Speed was the side's senior professional, expressed his gratitude for the help the midfielder gave him at the club.
"It is a sad, sad day. I played with him when I came through the ranks,'' Taylor told Radio Five Live. "He helped me through, he was an absolute machine - the best professional in football. He had that aura about him. He always had time for the young lads and helped them feel good about themselves.''