Sebastian Fundora has pulled off an upset…

In one of the bloodiest fights in recent memory, the 26-year-old Mexican American boxer scored the upset with a split-decision victory over Tim Tszyu to capture the WBC and WBO junior middleweight titles on Saturday night at T-Mobile Arena.

One judge scored the fight for Tszyu, 116-112, but was overruled by 116-112 and 115-113 tallies for Fundora. If Tszyu won the final round, the Australian star would have pulled out a draw.

Nicknamed “The Towering Inferno” for his gangly, 6-foot-5 ½ 154-pound frame, Fundora replaced Keith Thurman (ruptured biceps) on 11 days’ notice and stepped into his first title shot coming off his first defeat.

Last April, Fundora (21-1-1, 13 KOs) suffered a seventh-round knockout loss to Brian Mendoza in one of the year’s biggest upsets. He entered the ring a decided underdog and lost the first two rounds on all three cards.

However, the fight seemed to change when Tszyu (24-1, 17 KOs) suffered a deep gash on his forehead late in Round 2 due to an accidental elbow from Fundora.

Given the nine-inch height difference, such an accident was more likely than usual.

The blood never stopped flowing into Tszyu’s eyes for the remainder of the bout. The ringside doctor threatened to halt the fight following Round 3 but allowed it to continue. Tszyu, 29, never complained and never stopped coming forward.

“I’m an old, throwback fighter,” said Tszyu, who entered the night rated No. 2 by ESPN at 154 pounds. “I couldn’t see, but all credit goes to the man who won tonight. These things happen. The momentum was rolling, swinging hard in the first two rounds, and then boom, you’re blinded completely.

“This is boxing and this is part of the sport. Congratulations to Fundora. He’s the new king of 154. We’ll bounce back.”

Fundora also faced serious adversity. His nose bled profusely from the opening round onward, and his mouth was pouring blood as well. It made for a scene out of a horror flick, with both fighters’ faces crimson masks.

It made for great action, too, as Fundora and Tszyu furiously exchanged in a slugfest for two 154-pound titles.

“I didn’t want to break my nose today, but … this is boxing, you’re going to get hurt and you just have to be smart,” said Fundora, who entered the ring as ESPN’s No. 5 boxer at 154 pounds. “He’s a world-class fighter. He was a world champion for a reason.”

Fundora executed a disciplined game plan and used his long southpaw jab to pepper Tszyu from range. He was never dragged into a firefight, unlike in past fights, particularly Fundora’s 2022 TKO win over Erickson Lubin, in which he was floored, and in his loss to Mendoza, when he was up wide on the cards before being stopped.

“I’ve been telling everybody this whole camp, I’m gonna use my brain,” said Fundora, who fights out of Coachella, California. He was lined up for a fight with Serhii Bohachuk on PBC PPV on Prime Video undercard before he received the call to replace Thurman.

With the victory, Fundora and his sister Gabriela became the first brother and sister to be full-fledged champions in boxing history. Gabriela retained her IBF flyweight title in January with a TKO victory over Christina Cruz.

“It means the world,” Fundora said.

Tszyu, the son of Hall of Fame boxer Kostya Tszyu, broke out last year with a trio of victories. Last March, he scored a career-best win with a stoppage of former champion Tony Harrison two months after he was set to fight Jermell Charlo for the undisputed championship. That bout was canceled due to Charlo’s hand injury.

Tszyu stayed busy with a first-round knockout victory over Carlos Ocampo and then outpointed Mendoza in October. Afterward, Tszyu announced that he would campaign in the U.S. moving forward as he set his sights on the marquee fights.

Thurman presented a recognizable name to raise Tszyu’s profile, but his injury changed plans 11 days out. Tszyu adjusted on the fly to a 6-foot-5½ southpaw after he prepared all training camp for a 5-foot-8 orthodox boxer.

And Tszyu appeared in control against Fundora until the cut. He landed some powerful shots down the stretch, but Fundora’s active jab won the fight. Tszyu had been looking ahead to potential summer showdowns with Terence Crawford or Errol Spence Jr., but a rematch with Fundora could loom.

Fundora might have other ideas, however.

Spence, who was dominated by Crawford via ninth-round TKO in July for the undisputed welterweight championship, entered the ring afterward and called for a shot at Fundora next.

“It’s time to get it on,” Spence said. “He got a pretty good height, but we’ll see. We’ll break him down like we always do.”