Mark McCormack, once dubbed the most powerful man in sport, died on Friday after failing to recover from a heart attack he suffered four months ago, his International Management Group company said.
McCormack, 72, the founder, chairman and CEO of IMG, had been in coma at a New York hospital since January 16.
He was a pioneer and founder of the sports marketing industry and IMG was widely known as the world's largest representative of sportsmen and sportswomen.
"It's a loss for everybody," said Tiger Woods, the world's number one golfer and a client of IMG, after hearing the news at the Tour Players' Championship in Gut Kaden, Germany.
"He was a genius when it came to sports marketing and, obviously, with his association with Arnold, Jack and Gary, they basically started sports marketing. If it wasn't for him, obviously, we wouldn't be in the position we're in right now."
McCormack began his sports career in 1960 by signing golfer Arnold Palmer and, as his business grew, he played a key role in how much athletes were paid and how their images were portrayed.
Palmer never forgot the moment McCormack struck that first deal. "Mark has never broken the faith of that handshake. That meant a lot to me," Palmer said years later.
McCormack's company, based in Cleveland, grew rapidly and now has 80 offices in 32 countries.
First Clients
IMG represents a host of athletes ranging from McCormack's first clients, such as golfers Palmer, Jack Nicklaus, Gary Player and Olympic ski champion Jean-Claude Killy, to tennis players Pete Sampras and sisters Serena and Venus Williams.
The company, which has over 3,000 employees and sells more than 5,000 hours of television programming to over 200 countries around the world, has also represented tennis players Rod Laver, Bjorn Borg, John McEnroe, Martina Navratilova, Chris Evert and Andre Agassi.
McCormack's reach had stretched much further than the world of sport. He had even handled special projects for global leaders, such as former British prime minister Margaret Thatcher and the Pope.
Chicago-born McCormack had to overcome a fractured skull at the age of six when he was hit by a car. Unable to play contact sports, he took up golf -- the game that would change his life.
McCormack learned to play with his father and George E Q Johnson, the Chicago prosecutor who put Al Capone behind bars, as well as poet-historian Carl Sandburg, his godfather. Later, he qualified for the US Open as an amateur.
McCormack graduated from Yale law school and, after a spell in the army, joined Cleveland law firm Arter & Hadden and while working for the firm shook on his first deal with Palmer.
A prolific author of business books, McCormack's works included the best-selling What They Don't Teach You at Harvard Business School and Hit The Ground Running.
McCormack's personal philosophy was: "Be the best, learn the business, and expand by applying what you already know."
He leaves a wife, former tennis professional Betsy Nagelsen, four children and seven grandchildren.
A private burial will be held in Chicago followed by a memorial in New York on May 21.
