The former WBO junior middleweight champ comfortably beat Spence unanimously on points in their 12-round main event at Afterpay Arena in Tszyu’s hometown of Sydney, Australia. Spence (28-2, 22 KOs) lost a second straight bout, this time in the former IBF/WBA/WBC welterweight champion’s debut at the middleweight limit of 160 pounds, and acknowledged afterward that he will retire.

Judges Carlos Costa (117-111), Adam Height (118-110) and Ioana Schwalger (117-111) all scored Tszyu the winner by wide distances.

“One-sixty is my new division and I feel strong,” Tszyu said during his post-fight interview. “And a big blessing to my fans, man. This was one hell of a show. … I thought the Tony Harrison win was good, but let’s go party!”

Tszyu (28-3, 18 KOs) won his third consecutive fight following a technical-knockout loss to WBC 154-pound champ Sebastian Fundora a year ago in Las Vegas. He fought for the first time with Australian legend Jeff Fenech in his corner.

Spence, 36, fought for the first time in almost exactly three years. The DeSoto, Texas native’s performance reflected his age and inactivity, as Spence didn’t resemble the fighter who was considered one of boxing’s best pound-for-pound before Terence Crawford stopped him in the ninth round of his previous bout.

“It was a good fight,” Spence said. “Congratulations to Tim, Jeff Fenech. … It was a good showing by Tim. I answered a lotta questions for myself. Now it’s time to go home with my family and, you know, start a new life. I got my faculties intact. You know what I’m saying? My money is good and working for itself, so everything’s good, man.”

Spence surprised skeptics by skipping a tune-up fight that could’ve helped him shed the ring rust that accumulated since Crawford dropped him three times and dominated him in their long-awaited, 147-pound title unification fight in July 2023 at T-Mobile Arena in Las Vegas.

Injuries sustained during a one-car accident in October 2019 and retina surgery that cost him a scheduled fight against Manny Pacquiao in August 2021 also kept Spence largely inactive over the past seven years. His fight against Tszyu was just the fourth for Spence since he edged Shawn Porter in their welterweight championship unification clash in September 2019.

Despite Spence’s inactivity, Tszyu, 31, produced the most noteworthy win of his 10-year professional career against an opponent Tszyu believes belongs in the International Boxing Hall of Fame. The son of former junior welterweight champ Kostya Tszyu needed this type of victory versus an opponent as accomplished as Spence after losing two of his prior five fights by technical knockout to former IBF junior middleweight champ Bakhram Murtazaliev (23-1, 17 KOs) and Fundora (24-1-1, 16 KOs).

With swelling around his right eye, a fatigued Spence seemed content to go the distance during the 12th round. A persistent Tszyu drilled him with a right that snapped Spence’s head back and backed him into a corner with about 1:20 remaining in their fight.

Ronnie Shields, Spence’s new trainer, implored him to let his hands go before the 11th round. Spence obliged in the first half of it, but he couldn’t hurt Tszyu, who stung Spence with multiple right hands in the second half of the 11th.

Tszyu picked Spence apart to the head and body during the ninth and 10th rounds. Spence couldn’t keep the younger fighter from coming forward and didn’t land many consequential punches until the final minute of the 10th.

Referee Will Soulos sternly warned Spence for a foul for the second time in their fight a little less than a minute into the eighth round. Tszyu landed hard punches to Spence’s head and body before that warning.

An assertive Tszyu tried to build on his momentum at the start of the seventh round. He landed rights to Spence’s head in the opening minute and connected with another one that got Spence’s attention with 1:05 to go in the seventh.

Spence attempted to slow Tszyu down by attacking his opponent’s body in the sixth round. Tszyu connected to Spence’s body and head in the final minute of the sixth, which mostly made Spence retreat.

Tszyu’s right knocked Spence into the ropes and made him hold with just under 20 seconds on the clock in the fifth round. By then, swelling worsened beneath Tszyu’s left eye.

A right by Tszyu landed just after the halfway point of the fourth round. A left hook by Tszyu about 40 seconds later affected Spence, who moved away from him.

Tszyu landed multiple rights in the final 35 seconds of the third round, which drew blood from Spence’s nose.

Tszyu stumbled after their legs got tangled about 30 seconds into the third. Soulos warned Tszyu approximately a minute later for hitting Spence behind his head.

Spence’s left landed flush with just over 30 seconds to go in the second round, but Tszyu didn’t appear hurt by that shot. Spence seemed to take Tszyu’s punches better in those three minutes as well.

Tszyu landed two straight rights with just under a minute to go in the first round. Spence stumbled several seconds later and Tszyu capitalized by landing a right uppercut that knocked him off balance.

Spence connected with a straight left later in the opening round to get Tszyu’s respect. Spence previously landed a left hand to Tszyu’s head just after the midway mark of the first round.

Eleven rounds later, Tszyu expressed pride after beating one of the most formidable fighters of this era.

“I’d love to fight for a world title, man,” Tszyu said. “Who’s there? [Erislandy] Lara, yeah, guys like that. You know, like that’s where I’m aiming for. I wanna win a world title, but I gotta say, beating a great like Errol Spence tops any world title off for me.”