“I was catching him with shots the first day we sparred. The second day we sparred, those shots were not landing,” Mendoza said to FightHype.

“People forget he was a high-IQ boxer as an amateur.”

Mendoza said the biggest takeaway was watching Spence make adjustments from one sparring session to the next rather than simply relying on experience.

“For those of you that think he’s done, that he’s just showing up for a paycheck… he’s not working like someone who’s showing up for a paycheck.

“The work ethic I got to see in the couple of weeks I was in camp, and just from being in the ring with him… there were adjustments every day. He’s not someone that’s just showing up.”

Mendoza also addressed another major question surrounding Spence following such a lengthy layoff: whether he can still take a punch.

“I did check Spence’s punch resistance—I can definitely say I sent some missiles his way—and I honestly feel like he responded well.”

Mendoza is in a unique position to compare the matchup, having lost a unanimous decision to Tszyu in October 2023 before recently helping Spence prepare for the Australian.

Both fighters enter the bout looking to revive their careers. Spence has not fought since losing his WBC, WBA and IBF welterweight titles to Crawford, while Tszyu is trying to rebound after defeats to Sebastian Fundora and Bakhram Murtazaliev left his standing among the division’s elite in doubt.

With both men attempting to prove they still belong at the highest level, Mendoza’s assessment suggests Spence is arriving in Australia with more left in the tank than many critics have assumed.