He had been diagnosed in mid-July with soft tissue sarcoma, a cancer of the connective tissues, said Bob Kramer, one of his sons.
It was his 1947 U.S. title that led to changes in a sport that had been, for the most part, hypocritical. Players competed for trophies and nothing else. At least that's what they said.
"The amateur game was phony," Kramer said years later. "Kids were all getting money under the table."
So when he took the court for the '47 U.S. final, Kramer had made a decision that would affect the sport forever, a decision that prompted Hall of Fame tennis journalist Bud Collins to say Sunday, "From a competitor to an administrator to a broadcaster, Jack Kramer was the most important figure in the history of the game."
Before that '47 U.S. final, Kramer had decided to turn pro.
"It was simple," he said. "I needed the money."
A deal was in hand with a tennis promoter and needed only a top performance from Kramer in the tournament. But that looked shaky when he lost the first two sets of a best-of-five final to Frankie Parker. He recalled that he looked into the stands to find the man with whom he had cut the deal, but all he could see was his bald head, because the man was sitting with his face in his hands.
Either inspired or petrified, Kramer won the next three sets, losing only four games on the way to the title and setting the stage for tennis' pro era to take off. Two months later, his pro tour, a night-to-night barnstorming of cities across the world, attracted a crowd of 15,411 to Madison Square Garden -- in the middle of a blizzard.
Soon the success of the pro tours, Kramer's the most prominent, put pressure on the tennis federations, whose tournaments were no longer offering fans all the best players. That pressure eventually led to the establishment of Open tennis in 1968, featuring prize money for all players.
Kramer, who had served in World War II as a Coast Guard officer on landing craft in the Pacific, suffered from an arthritic back and by 1954 was finished as a player. But the cause of other players remained a motivation for him, and by 1973 he had become executive director of the Assn. of Tennis Professionals, the predecessor of today's ATP World Tour.
In '73, Niki Pilic refused to play on Yugoslavia's Davis Cup team, and his suspension by the International Tennis Federation extended through the dates of Wimbledon that year. When Wimbledon honored that suspension and refused to let Pilic play there, Kramer led a player boycott, Wimbledon ended up with a less-than-quality field and Kramer had helped players gain even more control of their game.
"He was a huge figure in tennis," said Rod Laver, who came along a generation later and said he benefited greatly from Kramer's pioneering. "We all needed money and he helped a lot of players get some."
Kramer's antiestablishment stances occasionally cost him.
The year after he won the Wimbledon title, he went to watch his close friend Ted Schroeder of San Diego play there.
"The year before, a member of the royal family had handed me a trophy," Kramer said a few years ago. "But this time, I was a pro. They wouldn't even let me in the locker room."
Collins, who did many broadcasts with Kramer and said he was excellent -- "Never over-talked" -- remembered how Kramer was treated after the '73 Wimbledon boycott.
"The BBC banned him," he said.