Leon Spinks, the heavyweight boxer who became undisputed world champion by upsetting Muhammad Ali in 1978 before losing a rematch only months later, has died. He was 67.

Spinks died on Friday, and had been suffering from prostate and other cancers, the Associated Press reported, citing a news release.

Spinks was a 24-year-old unheralded boxer with just seven professional bouts before meeting Ali — 36 years old and in the twilight of his career — in Las Vegas on Feb. 15, 1978. The fight went the full 15 rounds and at the end, when Spinks won by a split decision, Ali's face was badly bruised while Spinks looked fresh as he flashed his famous gap-toothed grin.

https://americanmilitarynews.com/2021/02/marine-vet-leon-spinks-boxer-who-took-title-from-muhammad-ali-dies-at-67/

One of my all time favorites.  The guy defied all odds.

He was well under the belt for that title.