The news seemed unimaginable, much as it might have 78 years ago when Yankees fans learned Lou Gehrig was diagnosed with the disease that would later bear his name.
It came on a Sunday night via a more modern form of communication, a Twitter feed. Dwight Clark didn't need the full 140 characters to stun football fans everywhere.
''I wanted to share some unfortunate news: I have ALS,'' Clark tweeted .
The receiver beloved and lionized in the Bay Area for ''The Catch'' now has weakness in his right hand, back and right leg. He can't play golf anymore, can't go for a run and can't walk any distances.
The only tidbit of anything resembling good news is that the disease is progressing slower than it has in some patients.
That doesn't mean it won't be just as debilitating. It certainly doesn't mean it won't be fatal, because ALS always is.
That it came because of football can't be proved. But the player immortalized in football history by the 1982 catch on a throw from Joe Montana that won the NFC title game for the 49ers over the Dallas Cowboys has an idea that it does.
''I've been asked if playing football caused this,'' Clark, now 60, wrote in another post. ''I don't know for sure. But I certainly suspect it did. And I encourage the NFLPA and the NFL to continue working together in their efforts to make the game of football safer, especially as it relates to head trauma.''
It was part of a disturbing weekend for both fans of football and the players who risk their future in the sport. The same day Clark announced his diagnosis, columnist Vahe Gregorian wrote a piece in the Kansas City Star about spending seven hours at the house of Gale Sayers.
Sayers, the Chicago running back considered one of the greatest NFL players ever, barely spoke during the visit. He's battling dementia, and his wife said some days are better than others.
Just before dinner, Gregorian wrote, Sayers went to wash his hands with carpet cleaner.
''It keeps you on your toes,'' Ardie Sayers said. ''Don't let him out of your sight.''
The link between football and brain damage is by now well documented. After decades of denial a top NFL executive belatedly acknowledged to Congress last year that there is a link between football and neurodegenerative diseases such as chronic traumatic encephalopathy.
Jeff Miller, the NFL's senior vice president for health and safety, said he based his opinion on the work of Boston University neuropathologist Ann McKee, who as of last month had diagnosed CTE in the brains of 97 out of 101 former football players examined after death.
Some former players have been diagnosed with CTE-like symptoms while still alive. That includes Tony Dorsett, the Dallas Cowboys running back who is ninth on the all-time career list with 12,739 rushing yards.
Dorsett told the Fort Worth Star Telegram last month that he's fighting CTE and had no idea ''that the end was going to be like this.''
That the players of Dorsett's era didn't know how they might end up isn't surprising. The NFL paid little attention to how hits to the head might affect players in their later lives, and the science about the effects of head hits and concussions was still young.
That's changed, and now every player who comes into the league should be aware of the danger. Concussion protocols have also changed drastically, though nobody knows for sure how much protection that offers.
`'This used to be a different league,'' DeMaurice Smith, head of the NFL players' union said last month at the Super Bowl. `'If you stumbled to the sideline, somebody maybe pushed you back in.''
Still, players continue to risk their health, even knowing the possible consequences. At the same NFLPA press gathering where Smith spoke, Giants linebacker Mark Herzlich - who survived cancer to play in the NFL - talked about suffering his third concussion in a November game against the Browns.
Yet Herzlich came back to play. He still wants to play, no matter how uncertain his future might be.
Football players are tough guys. They have to be to survive in a sport where the toughest always come out on top.
Some play the game because they love it. Others play it because it can make them wealthy
Unfortunately, most don't see 30 years into the future. They think they're invincible, and that bad things will only happen to other guys.
But with each new and terrible diagnosis we're reminded of the price our football heroes continue to pay.
Tim Dahlberg is a national sports columnist for The Associated Press. Write to him at tdahlberg(at)ap.org or http://twitter.com/timdahlberg