Yet the 36-year-old, who called it a career during his in-ring interview and doubled down an hour later during the press conference, is proud to depart the sport with his faculties intact. 

"It didn't go the way I wanted, but much respect to Tim. He was timing [his punches] real well and my timing ... kinda off," he said in the post-fight presser. 

He shared the dose of reality that convinced him time had caught up with him and retirement was rearing its head: He struggled to go the 12-round distance.

"Realizing how long it was ... it's a sign to hang 'em up because [doing] those rounds usually isn't that long but it was," he said. "I don't remember it feeling like that. That's how I knew. You can't be off that long, come back and think you can fight a 12-round fight with a caliber of opponent like that."

Before he was stopped in nine rounds by Terence Crawford for the undisputed 147-pound championship in July 2023, Spence (28-2, 22 KOs) had gone the 12-round distance in three consecutive defenses between March 2019 and December 2020.

He stopped WBA beltholder Yordenis Ugas in the 10th round of their April 2022 three-belt unification, although injuries and lengthy inactive spells didn't help his cause as wear and tear had begun to pile up.

Spence insisted that while there was "a lot of stuff" he couldn't do from his prime years against Tszyu, there was nothing wrong with his training camp.

The Texan is looking forward to being a "soccer dad" again and spending time with his family knowing there's no need to fight anymore.

"I'm most proud of keeping my faculties and having enough money in the bank, even before this, to retire and live the same life 10, 20 years from now and still be OK," he said. "I'm in a sport where a lot of boxers – Hall of Fame or not – retire broke. Even if I didn't have this fight, I still would've been OK."

Spence said that Tszyu was the first opponent to ask him for post-fight advice on what he can improve going forward and wondered aloud when asked to rate the Aussie's chances against the likes of Erislandy Lara (32-3-3, 19 KOs) andJermell Charlo (35-2-1, 19 KOs).

No Limit Boxing had rolled out the red carpet for Spence, who many expect to be a first ballot Hall of Fame inductee when he's eligible at the end of the decade.

Promotional chief Matt Rose had the final word and thanked the departing legend for producing an admirable effort – all things considered – down under while embracing a new environment.

Spence was given a warm welcome at Sydney airport with a ceremony on arrival arranged by the Rose brothers, which left a lasting impression on him as he embraced the Aboriginal performers.

He walked out to Archie Roach's "Took the Children Away," a song detailing the government-sanctioned removal of Aboriginal children from their families in Australia (1910-1970), and spoke plenty during fight week about how learning about the past had inspired him.

"It was an honor to have Errol come out to our country," Rose said in an impromptu speech.

"We've always been big fans our whole life following his career. It's a special moment for us and the way you've embraced our culture meant a lot. To even find out this was your last fight, we'll remember this forever. Thank you for being the person and legend you are. You'll go down in history as one of the greatest welterweights of all-time."