CARSON, Calif. -- Twelve thrilling rounds couldn't separate Jermell Charlo and Brian Castano when they met in July, and 10 months later not much changed through nine rounds.
Wild, brutal exchanges that lifted the spirited crowd at Dignity Health Sports Park. Numerous difficult-to-score rounds. A back-and-forth pitched battle from bell to bell.
Finally, a series of shots -- a right hand to the body followed by a left hook to the head -- changed the fight for good. Castano crumbled in a heap in Round 10 of an instant classic Saturday, a PBC on Showtime rematch that topped the first fight that ended in a draw.
Somehow, someway, Castano made it to his feet before the count of 10, but his courage was simply a precursor to the swift end. The Argentine was in no shape to continue, and Charlo sensed the moment.
He sprinted over to Castano and unleashed a series of lefts and rights that floored him one final time, then headed to the turnbuckle to celebrate as the referee counted to 10 with seven seconds remaining in the round. For the second time, Charlo scored a knockout in a title rematch (vs. Tony Harrison in 2019) and now he's the undisputed 154-pound champion after adding Castano's title to the three he already owned.
"I showed the fans, I showed these haters I can stand there and trade," said Charlo, who was ahead 87-84, 88-83 and 89-82 entering Round 10. "One thing I changed up is try not to be on the ropes too much ... place shots on really precise parts on the body and wear him out."
Round 10 was the same frame in which Charlo (35-1-1, 19 KOs) landed his fight-changing shot 10 months ago. Castano (17-1-2, 12 KOs) was in control of the first meeting when Charlo badly hurt him with a counter left hook, but he never went down. Castano appeared to win that bout, but was only ahead on one scorecard, 114-113 (the other scores were 114-114 and 117-111 for Charlo).
This time around, Charlo was far sharper. He landed effective counterpunches off the ropes. His jab and movement allowed him to escape trouble and eventually led to the punch that ended the rivalry and welcomed boxing's ninth male undisputed champion of the four-belt era.
"He was smarter this time," said Castano, 32. "I felt that I won the first fight but tonight he caught me and that was it. ... I feel like I still have a lot to give in boxing. ... I'm happy with my performance despite the loss. I feel like there's big room for corrections and improvements with my boxing."
But it was Charlo who made the proper corrections to earn the biggest win of his career. Trainer Derrick James said he instructed Charlo to shoot his shots to the shoulder to catch Castano with follow-up punches when the Argentine was ducking. The strategy worked.
"We were breaking him down," James said.
The first six rounds featured nonstop slugging at a frenetic pace, and Charlo was able to match Castano punch for punch. Castano, as always, applied constant pressure and was able to slip in a bundle of sharp left hooks that landed flush.
"His plan is to get in good shots at the end of the round," said Charlo, whose twin brother, Jermall, is a middleweight titleholder. "I said to myself, 'I gotta stay stronger.' I was trying to tune out everybody else."
Charlo, who is from Houston, ate the shots and really took over in Round 7 after he buckled Castano with a left hand. He didn't follow up but the opportunity presented itself again three rounds later. And he capitalized.
Now, Charlo, 31, can't be denied as the ruler of the junior middleweight division after yet another definitive victory in a rematch.
"I'm durable, I was going all 12, and unfortunately my power gets stronger by the rounds," Charlo said. "I ain't done yet. I'm still learning and growing. I can learn from this fight. ... I'm tough to beat."