"He was a giant in the NFL," New York Jets owner Woody Johnson said. "Gene continually served in the best interests of the game of football. He played a colossal role in the success the NFL enjoys today, even more than many people realize."
His death was first reported by Clear Channel Online that appeared on several radio Web sites.
Upshaw's death came only two days after the union announced he would hold a briefing on labor negotiations before the Sept. 4 season opener between Washington and the New York Giants.
His outstanding 15-season playing career was entirely with the Oakland Raiders and included two Super Bowl wins and seven Pro Bowl appearances. Upshaw's biography was posted on the front page of the Hall of Fame Web site Thursday along with his enshrinement speech from 1987.
In 1983, he became executive director of the players' association and guided it through the 1987 strike that led to replacement football. By 1989, the players had a limited form of freedom, called Plan B, and in 1993, free agency and a salary cap were instituted.
Since then, the players have prospered so much that NFL owners recently opted out of the latest labor contract, which was negotiated two years ago by Upshaw and then-commissioner Paul Tagliabue.
Upshaw was criticized by some for not being tough enough in talks with Tagliabue, a close friend of the union head. He also was blamed by many older veterans for not dealing sufficiently with their health concerns.
But the salary cap for this season is $116 million and the players are making close to 60 percent of the 32 teams' total revenues, as specified in the 2006 agreement. In all, the players will be paid $4.5 billion this year, according to owners.
Upshaw recently became more aggressive in his dealings with the owners and Tagliabue's successor, Roger Goodell. Owners opted out of the collective bargaining agreement, which means a season without a salary cap in 2010. Upshaw declared the cap would disappear for good should there be no new deal by March 2010.
"I'm not going to sell the players on a cap again," Upshaw said. "Once we go through the cap, why should we agree to it again?"
NFL officials claimed players are getting a disproportionate amount of the revenue. Upshaw's supporters said management's viewpoint indicates he did his job well.
The players called a strike in 1987 -- leading to games with replacements -- and it wasn't until 1993 that labor peace was reached with a breakthrough seven-year contract. It included free agency and a salary cap. Almost ever since, player salaries have spiraled up along with revenue from television and marketing deals made by the league.
The NFLPA also has its own marketing arm, Players Inc., established in 1994, that has grown into a multimillion dollar operation.
Frequently was listed as one of the most powerful men in U.S. sports, Upshaw was drafted in the first round by Oakland in 1967 out of Texas A&I -- hardly a football factory. He was an NAIA All-American at center, tackle and end, but was switched to left guard by the Raiders.
And that's where he stayed through a magnificent career that included 10 conference championship games as well as the Super Bowl victories.