Scottish boxing great Ken Buchanan, who became the undisputed world lightweight champion in 1971 and won his first 33 fights, has died at the age of 77.
His death was announced Saturday in a Facebook post from the Ken Buchanan Foundation, which read: "It's with great sadness that we have to inform you that Ken Buchanan passed away peacefully in his sleep this morning.
"Further announcements will come and please give the family some time to process this sad news. RIP Ken, always a gentleman and one of the best champions we will ever see."
Buchanan's son said last year that the former boxer was suffering from dementia and living in a nursing home.
Buchanan won the WBA lightweight title in 1970 by defeating Ismael Laguna in a famous fight in Puerto Rico and added the WBC crown the following year with victory over Ruben Navarro. He was named the 1970 Fighter of the Year by the Boxing Writers Association of America ahead of heavyweights Muhammad Ali and Joe Frazier.
Buchanan was stripped of the WBC title for failing to defend it against Pedro Carrasco and then lost the WBA belt to Roberto Duran in controversial fashion.
After taking an apparent low blow to the groin at the end of the 13th round, Buchanan was unable to come out for the 14th, and the referee awarded the fight to Duran, who had been comfortably ahead on points. There was no rematch.
Buchanan, who finished his career with a 61-8 record, fought for the final time in 1982.
"Sad to hear Scotland's first undisputed champion of the world Ken Buchanan has died," Humza Yousaf, the first minister of Scotland, tweeted. "He inspired and mentored a generation of boxing talent here in Scotland and beyond. Rest in peace Champ."
A statue of Buchanan in his home city of Edinburgh was unveiled last year.
The Associated Press and Reuters contributed to this report.