Gene Upshaw, the NFL star turned players' union head who was instrumental in securing huge wealth for his members, has died aged 63.
After a 15-year career with Oakland, including two Super Bowl wins, he became executive director of the NFL Players' Association in 1983.
He led the NFLPA through a strike in 1987, and by 1989 the players had won a limited form of free agency.
In 1993, full free agency was agreed, meaning bigger signing fees and wages.
The current NFL labour deal, negotiated in 2006 by Upshaw and then-commissioner Paul Tagliabue, has seen the players taking 60% of the total revenue of the league's 32 teams.
In total, the players will be paid $4.5bn this year, according to club owners.
"It is a sad day for the NFL, but Gene's positive impact and legacy will live on for decades to come"
The owners recently opted out of the latest labour contract, raising the prospect of fresh conflict between the NFLPA and the teams.
Upshaw died following a short illness after he was diagnosed with pancreatic cancer.
In a statement, the NFLPA said: "We are deeply saddened and shocked by the sudden and unexpected death of our leader, Gene Upshaw.
"Our thoughts and prayers go out to his wife, Terri, and their three sons, Eugene, Justin and Daniel. Gene learned he was sick just this past Sunday and he died with his family at his side."
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"He was the rare individual who earned his place in the Pro Football Hall of Fame both for his accomplishments on the field and for his leadership of the players off the field.
"It is a sad day for the NFL, but Gene's positive impact and legacy will live on for decades to come."
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