Sebastian Fundora sensed something was wrong with Tim Tszyu before their rematch two months ago.

Fundora doesn’t know exactly what bothered the former WBO junior middleweight champion during fight week in Las Vegas. Whatever it was, Fundora feels it adversely affected Tszyu when they fought for the 6-foot-6 southpaw’s WBC super welterweight title July 19 at MGM Grand Garden Arena.

Fundora, who will face Keith Thurman on October 25, beat Tszyu by technical knockout in their second meeting because he declined to answer the bell to start the eighth round. Tszyu was knocked down during the first round and trailed by the same score, 69-63, on all three cards when their bout abruptly ended.

The dejected Australian admitted afterward that Fundora’s relentlessness wore him down and made Tszyu feel like whatever he did wouldn’t be enough.

From Fundora’s perspective, he had an advantage over Tszyu before the opening bell on the Manny Pacquiao-Mario Barrios undercard.

“You’ve gotta ignore all the extras and remain focused,” Fundora told The Ring. “Remain focused on what you want and what you’re doing. And our fight weeks, both fight weeks, there was just something blocking [his mind]. And you could see it during the faceoff or whenever we interacted with each other.

“You could see something was bothering him. And again, this is the World Series. You cannot do things like that. Those are mistakes that you will take into the fight.”

Though Bakhram Murtazaliev tends to get credit for ruining Tszyu on October 19, Fundora feels he was the opponent who changed him in their first fight.

Fundora won that bloodbath by split decision in March 2024. Tszyu (25-3, 18 KOs), whose head inadvertently hit Fundora’s elbow late in the second round, fought through a ghastly gash in the middle of his hairline for 10 rounds.

Russia’s Murtazaliev (23-0, 17 KOs) dropped Tszyu four times, three times in the second round and once in the third. Tszyu entered the ring as a 7-1 favorite, but Murtazaliev overwhelmed him to successfully defend his IBF junior middleweight belt.

“They’re gonna have a different mindset on fighting forever now, after that first fight,” Fundora said. “I think he definitely took a lotta damage in the first fight. I don’t think he took too much damage versus [Murtazaliev]. It’s just, again, after that first fight they’re gonna be worried about their fighter. And he’s gonna be worried himself. We saw how he came out that first round versus [Murtazaliev]. He wasn’t focused at all. You could see him touching for a cut. And a lotta people still don’t wanna give me credit at all for that.”

Fundora (23-1-1, 15 KOs), of Coachella, California, and Thurman (31-1, 23 KOs, 1 NC), of Clearwater, Florida, will headline a Premier Boxing Champions pay-per-view show. DraftKings lists Fundora as more than a 4-1 favorite to beat Thurman, a former WBA/WBC welterweight champ.