It was the battle of the champs, and not just according to LIFE Magazine’s headline: Muhammad Ali and Joe Frazier, two undefeated boxers, would meet head to head on March 8, 1971. Each would take home a whopping $2.5 million purse. Fans were eager for insight into the preparations so, for a LIFE cover story leading up to the bout, both men—the disciplined Frazier and the loose Ali—gave the magazine’s reporters and photographers extensive access to their lives during training.

Which is where John Shearer came in. The photographer, then a young LIFE staffer, had met and photographed Ali before—but the lead-up to the 1971 fight was, he later recalled, something different. In October of 2014, Shearer sat down to talk to LIFE about his career, and that assignment.

“The Ali-Frazier fight story was certainly one of the more important stories in my life,” he recalled.

Ali had been away from the sport of boxing for three years, having lost his license over his refusal to fight in Vietnam. Fans worried he was rushing into his comeback, that he was out of shape, that he had lost his speed. (As the editor’s note in the issue mentioned, Shearer—who had spent weeks with both fighters—guessed that Frazier would win in 10 rounds.) But that didn’t mean that plenty of people weren’t rooting for Ali.

“He was the man. He was back,” Shearer said in 2014. “You know, they expected him to win. And so there was a lot of pressure.“

MORE: See Shearer’s Photographs From the Fight

Being Ali meant being “on” all the time, Shearer learned. Though he said that he felt able to gain real insight into Frazier’s life, with Ali he was always seeing the public persona. “Muhammad Ali, while I was with him, you know, every day, all day long, I didn’t get invited back into his home,” Shearer said. There might be glimpses of the introspective man behind the celebrity face, but Shearer didn’t feel he was eager to share that side of himself.

That situation didn’t change after the fight. Frazier won.

After, Shearer didn’t have the heart to go into Ali’s dressing room, the photographer recalled. He had known from the moment in the fight when Ali went down for a moment that Frazier would win. And, he said, he could see that Ali knew too. That look on Ali’s face was too much to take. So LIFE staffer Gordon Parks went in the loser’s room instead. (Parks and Shearer share more than an assignment: Parks was the magazine’s first African-American staff photographer and Shearer was the second.) Shearer stuck with Frazier, capturing images of the winner celebrating while looking, as the photographer puts it, “beaten pillar to post” but happy.

Though Ali would come back, and swinging, that pit-of-the-stomach sadness was a similar feeling to one the photographer would feel much later, seeing Ali as disease ravaged the boxer, who died last week. Seeing a man who is down can hurt more when you know what the man looked like at his best. And John Shearer saw better than most what Ali had been.

“You know, he was not perfect. No one’s perfect,” the photographer said. “But he was great.”

Write to Arpita Aneja at arpita.aneja@time.com and Lily Rothman at lily.rothman@time.com.

SPONSORED FINANCIAL CONTENT

Read More From TIME

EDIT POST