The sports world is mourning the death of boxing legend Leon Spinks.

USA Today reports the former heavyweight champion died Friday night at the age of 67, following a years-long battle with cancer. His wife, Brenda Spinks, was reportedly by his side at the time of his death.

The St. Louis native rose to prominence in 1978, when he defeated Muhammad Ali for the world heavyweight title. It was an especially shocking upset, as Spinks had entered the match with only seven professional fights under his belt, and was about 25 pounds lighter than Ali. 

“Ali thought I was a wimp and I had to prove to him I wasn’t,” Spinks recalled in 2014. “I knew I could beat him after watching his fights.”

The former U.S. Marine and Olympic gold medalist would continue to fight until 1995, retiring with a 26-17-3 (14 KOs) record. He was inducted into the National Boxing Hall of Fame in 2017.

Spinks experienced a number of health issues throughout his final years. In 2012, he was diagnosed with brain shrinkage due to the days he spent in the ring. He was hospitalized with abdominal problems two years later and had to undergo multiple emergency surgeries. He would go on to be diagnosed with prostate cancer, which reportedly spread to his bones

“Rest in peace, Leon Spinks,” World Boxing Council President Mauricio Sulaiman tweeted Saturday. “Olympic medalist, Pan American medalist, and of course, WBC heavyweight champion.”

You can read addition tribute posts for Spinks below.